Its funny I think the three early wonders mentioned are some of the best.
1. TGW. why? Admitedly, I sometimes play without barbs, but even when I don't, they don't seem that much of a hassle.. At least on this difficulty.. Also, the AI seems to love this one a lot, even when barbs are Off. o_o
The Great Wall On higher difficulty levels, barbs can be quite annoying. If you build this you can REX pretty freely. It could pay for itself in

s spent for

s not having to spend in units early on. Then there is the great spy. This bad boy can be used to steal 6 technologies in the early game and 4 a little later if you get a 2nd one. Focus your espionage on the leading techer, steal from him and then trade those around. This can be one of the greatest wonders.
2. The Oracle. Yeah, sure, you get a free Tech, but you also have to invest in priesthood path, witch dosen't seem that attractive.. Not as good as writing for your Civ and not a good Tech to grade as the AI gets it most of the time aswell.. The only time I want Oracle is when I go for a slingshot MC and try to nail mids of a great engineer. C-C-C-Combo Breaker!!
The Oracle This is a gamble. It often goes very early. If you have marble though, going for priesthood may not be as bad of an economic decision as it seems, for it opens up oracle and temple or artimitis
if you fail Oracle you might still be able to get TOA or the failure gold from it. Plus priesthood is on the way to monarchy, which can be a big economic boost.
As just one example of the many ways this wonder can be used, the Oracle can unlock Code of Laws if you have writing as well which can be huge but especially huge if you are HRE, Org, or in a position where creating a religion is optimal
then also you get priest

to make the shrine.
3. TGL. at first, it seems awesome, but I never seem to get that much out of it.. Maybe I don't plan for it but I was never impressed.
The Great Lighthouse Map dependent (as everything in this game is.) I play fractal. I didn't get into TGL until I played emperor...
REXing is simultaneously more competitive, important and expensive the higher level you play at...build this thing and coastal cities will pay for themselves immediately (maybe this isn't technically true in all instances but it seems to be in my experience)
Personally, I didn't really "get" the power of

s for a long time.
Great merchants arent bad either.
Just be sure to
1.) Make sure to explore (or trade maps when you can) AI coastal cities you have open borders with.
2.) Have open borders with AIs.
3.) Be ready for a mercantilism fad to send you crashing at some point...
And most of all!
4. Golden Age wonders. Mausoleum and Taj. Why? I just don't understand this.. Golden ages are nice but is it really worth it pumping so many hammers in Taj just for a GA?
Or mausoleum.. How many GA do you actually get during a game? 3 at most, I presume. So mausoleum = Taj. Is there smth I just don't see?
Taj I often build this because I pick nationalism from liberalism (because I dont have banking for economics or optics for astronomy.) So
often Taj is built simply because I can build it and others cant
But lets consider when this happens
around this time there are a lot of new civic options
also the extra

boost from a golden age can help build 6 universities and Oxford, which is huge
also the extra

can be good to pop a merchant to bulb economics if it is a close race
sure you didnt exactly get a great merchant at no cost but you did deny the AIs from getting it.
MoM- I dont build this one often. On kossins daily round thread, he did it sometimes to good effect.
Also, I see some wonders (sankore and angkor wat come to mind) that see much less love.. And in my eyes they seem much stronger..
I appreciate any words of wisdom..
You did not mention why you think Sankor or Angor Wat are much stronger.
Angor Wat is very niche
I think the burden of proof is on you to explain what makes it great.
Sankor isnt all that by itself
in some games Im barely building any temples. Coupled with SPI, Sistine, Spiral Minaret, or AP, Sankor can be nice
or if you wanted to stay in OR or Theoc for various reasons. Free Religion is often a better choice due to diplomatic reasons...when I was less experienced sometimes I let Sankor commit me to OR when I probably shouldnt have.