There is no question that God of Craftsmen will give more hammers over the course of the game. But that's not the entire equation.
To level set, MotG only applies to Ancient and Classical Era wonders (World Wonders and National Wonders). That list is (unless I've overlooked something) 14 World Wonders and 5 National Wonders:
Circus Maximus
Colossus
Great Library
Great Lighthouse
Great Wall
Hanging Gardens
Heroic Epic
Mausoleum of Halicarnasis
National College
National Epic
Oracle
Parthenon
Petra
Pyramids
Statue of Zeus
Stonehenge
Temple of Artemis
Terracotta Army
Writers' Guild
All of the World Wonders cost either 185 or 250 hammers (8 at 185 and 6 at 250), so call that an average hammer cost of about 210 per wonder. That means MotG will save you about 27 hammers per World Wonder without Aristocracy or marble (and will save about 24 hammers with either Aristocracy or marble). How many World Wonders are realistic? Well, that depends on difficulty level (wouldn't bother with it on Deity), and some require different policy tree openers (Statue of Zeus (Honor), Hanging Gardens (Tradition) and Pyramids (Liberty)), several (Petra, Great Lighthouse, Colossus) you may be unable to build due to city location, and others won't be there when you are ready to build them. But, let's be REALLY generous and assume you can build 10 of the 14 World Wonders, with a representative blend of those that cost 185 hammers and those that cost 250 hammers, AND that you had MotG for all of those wonder builds (a bit unrealistic, since Great Library and Stonehenge typically require early hammer investments). MotG in this scenario saves about 270 hammers (10 x 27) (240 hammers if you also have Aristocracy or marble).
Let's also assume that you build all of the Ancient/Classical Era National Wonders before you settle too many cities (or maybe you are playing Tall anyway), so let's assume a 30-hammer savings on the National Wonders (Writer's Guild is only 100 hammers to build, so 30 hammers overstates MotG for it, but Heroic Epic probably comes a lot later, so maybe it evens out...). Anyway, with 5 National Wonders, MotG saves approx. 150 hammers.
Total MotG hammer savings = up to approx. 420 hammers (more or less), many of which probably came before turn 150 or so. Let's put the turn 150 total at 250 hammers saved (probably overly generous, but 10 World Wonders is also pretty darn generous).
Now GoC: Let's assume you get the pantheon around turn 40 or so, that you settled your second city around that same turn (perhaps the start of a Tradition 4-city opener) and it got to 3 pop by turn 60 (pretty conservative). You then settled cities 3 and 4 right after finishing a 2-city NC build, but they each take until turn 100 to get to 3 pop (again, pretty conservative).
Under that scenario, GoC will provide 1 hammer per turn from turn 41 to turn 60 (20 hammers), 2 hammers per turn (cap and city 2) from turn 61 to turn 100 (40 hammers), and 4 hammers per turn in your 4 cities from turn 101 to the end of the game (perhaps you get a culture or diplo victory on turn 250) (600 hammers). Total from GoC: 660 hammers. Of this total, 260 came before turn 150, but mostly in the turn 101-150 time range. And the longer the game lasts and/or the more cities you have, the more valuable GoC is. And this is before you take account of potential puppets with your religion, spitting out an extra hammer as they crank out walls, castles, markets, banks, and other stuff that puppets build.
The punchline is that in this highly stylized example (10 of 14 World Wonders--really?), MotG gets off to a quicker start than GoC, which catches up around turn 150 and then leaves MotG in its wake.
Of course this ignores the snowball effect that early hammers can provide, particularly if those early hammers get wonders that will speed you along your path and/or provide more hammers themselves (e.g., Terracotta's free units, ToA's extra food that allows you to work an extra hammer tile or two in each city, etc.).
This is similar to the trade-offs involving the gold-giving Founder beliefs: Church Property, Initiation Rites and Tithe. Initiation Rites clearly gives the largest amount of upfront gold, Church Property is in the middle, and Tithe really hits its stride later in the game, as city populations rise, but provides paltry rewards when all you can see are 3- to 5-pop cities all around you.
To level set, MotG only applies to Ancient and Classical Era wonders (World Wonders and National Wonders). That list is (unless I've overlooked something) 14 World Wonders and 5 National Wonders:
Circus Maximus
Colossus
Great Library
Great Lighthouse
Great Wall
Hanging Gardens
Heroic Epic
Mausoleum of Halicarnasis
National College
National Epic
Oracle
Parthenon
Petra
Pyramids
Statue of Zeus
Stonehenge
Temple of Artemis
Terracotta Army
Writers' Guild
All of the World Wonders cost either 185 or 250 hammers (8 at 185 and 6 at 250), so call that an average hammer cost of about 210 per wonder. That means MotG will save you about 27 hammers per World Wonder without Aristocracy or marble (and will save about 24 hammers with either Aristocracy or marble). How many World Wonders are realistic? Well, that depends on difficulty level (wouldn't bother with it on Deity), and some require different policy tree openers (Statue of Zeus (Honor), Hanging Gardens (Tradition) and Pyramids (Liberty)), several (Petra, Great Lighthouse, Colossus) you may be unable to build due to city location, and others won't be there when you are ready to build them. But, let's be REALLY generous and assume you can build 10 of the 14 World Wonders, with a representative blend of those that cost 185 hammers and those that cost 250 hammers, AND that you had MotG for all of those wonder builds (a bit unrealistic, since Great Library and Stonehenge typically require early hammer investments). MotG in this scenario saves about 270 hammers (10 x 27) (240 hammers if you also have Aristocracy or marble).
Let's also assume that you build all of the Ancient/Classical Era National Wonders before you settle too many cities (or maybe you are playing Tall anyway), so let's assume a 30-hammer savings on the National Wonders (Writer's Guild is only 100 hammers to build, so 30 hammers overstates MotG for it, but Heroic Epic probably comes a lot later, so maybe it evens out...). Anyway, with 5 National Wonders, MotG saves approx. 150 hammers.
Total MotG hammer savings = up to approx. 420 hammers (more or less), many of which probably came before turn 150 or so. Let's put the turn 150 total at 250 hammers saved (probably overly generous, but 10 World Wonders is also pretty darn generous).
Now GoC: Let's assume you get the pantheon around turn 40 or so, that you settled your second city around that same turn (perhaps the start of a Tradition 4-city opener) and it got to 3 pop by turn 60 (pretty conservative). You then settled cities 3 and 4 right after finishing a 2-city NC build, but they each take until turn 100 to get to 3 pop (again, pretty conservative).
Under that scenario, GoC will provide 1 hammer per turn from turn 41 to turn 60 (20 hammers), 2 hammers per turn (cap and city 2) from turn 61 to turn 100 (40 hammers), and 4 hammers per turn in your 4 cities from turn 101 to the end of the game (perhaps you get a culture or diplo victory on turn 250) (600 hammers). Total from GoC: 660 hammers. Of this total, 260 came before turn 150, but mostly in the turn 101-150 time range. And the longer the game lasts and/or the more cities you have, the more valuable GoC is. And this is before you take account of potential puppets with your religion, spitting out an extra hammer as they crank out walls, castles, markets, banks, and other stuff that puppets build.
The punchline is that in this highly stylized example (10 of 14 World Wonders--really?), MotG gets off to a quicker start than GoC, which catches up around turn 150 and then leaves MotG in its wake.
Of course this ignores the snowball effect that early hammers can provide, particularly if those early hammers get wonders that will speed you along your path and/or provide more hammers themselves (e.g., Terracotta's free units, ToA's extra food that allows you to work an extra hammer tile or two in each city, etc.).
This is similar to the trade-offs involving the gold-giving Founder beliefs: Church Property, Initiation Rites and Tithe. Initiation Rites clearly gives the largest amount of upfront gold, Church Property is in the middle, and Tithe really hits its stride later in the game, as city populations rise, but provides paltry rewards when all you can see are 3- to 5-pop cities all around you.
Haven't played Rome in BNW yet, but doubt it's that cute now, since you'll have fewer cities as Rome in BNW anyway (goodbye to ICS) and you can always slap a food\production trade route into a new city.
