Let's see...
1. Small map means that you won't end up with 50 cities or so. This means micromanagement, such as city positioning, decisions regarding improvements, etc will remain having a big impact on your game. On large or huge maps, there is so much space you can virtually settle tons and tons of cities. Even with many enemies, you will eventually conquer some. And end up with the same 50 cities again. When you have so many, it barely matters whether you have another one, whether you have workshops or towns... It's micromanagement that makes this game enjoyable. Later on you won't even notice if you lose like 5 cities unless you lose a capital or those cities that you settled in great places.
2. Resources more important, since there is less spots for them to pop up. On huge map, even if you don't have, say, iron on your grounds, it barely matters since there is 1 million iron veins on the map anyway.
3. Less tedious warfare. Waiting 30 turns before your army reaches the enemy? Yawn.
4. I found out myself that cities beyond 10 or so barely had any impact on my game anyway. Cities I was founding in late game had 1/10 commerce of the developed ones. Sure, with a lot gold/Universal suffrage you can build a new building each turn, but it still takes time for the city to grow, work tiles, get ALL the necessary buildings... If you're for hut economy, it takes ages for the huts to grow into towns,too. My oxford town can generate like 10 x the beakers all my modern-era or even pre-modern era towns COMBINED can.
5. Since the AI goes ape**** when attacked and starts settling in every possible direction, it lessens the time needed to search for those stupid 1 pop settlements the AI massproduces during war.
Sure, no more epic battles with 1 million units... but arguably, they aren't that fun. Unless you like 1 pop settlements razing over and over again because AI makes crazy amounts of settlers during war and spreads them in every possible direction...
Also, once the main force (biggest, oldest towns + army) is down, arguably it doesn't matter whether there are 20 cities left to conquer or 5.
What do you think, what map size is optimal for max enjoyment throughout ALL game, not just the start?
1. Small map means that you won't end up with 50 cities or so. This means micromanagement, such as city positioning, decisions regarding improvements, etc will remain having a big impact on your game. On large or huge maps, there is so much space you can virtually settle tons and tons of cities. Even with many enemies, you will eventually conquer some. And end up with the same 50 cities again. When you have so many, it barely matters whether you have another one, whether you have workshops or towns... It's micromanagement that makes this game enjoyable. Later on you won't even notice if you lose like 5 cities unless you lose a capital or those cities that you settled in great places.
2. Resources more important, since there is less spots for them to pop up. On huge map, even if you don't have, say, iron on your grounds, it barely matters since there is 1 million iron veins on the map anyway.
3. Less tedious warfare. Waiting 30 turns before your army reaches the enemy? Yawn.
4. I found out myself that cities beyond 10 or so barely had any impact on my game anyway. Cities I was founding in late game had 1/10 commerce of the developed ones. Sure, with a lot gold/Universal suffrage you can build a new building each turn, but it still takes time for the city to grow, work tiles, get ALL the necessary buildings... If you're for hut economy, it takes ages for the huts to grow into towns,too. My oxford town can generate like 10 x the beakers all my modern-era or even pre-modern era towns COMBINED can.
5. Since the AI goes ape**** when attacked and starts settling in every possible direction, it lessens the time needed to search for those stupid 1 pop settlements the AI massproduces during war.
Sure, no more epic battles with 1 million units... but arguably, they aren't that fun. Unless you like 1 pop settlements razing over and over again because AI makes crazy amounts of settlers during war and spreads them in every possible direction...

What do you think, what map size is optimal for max enjoyment throughout ALL game, not just the start?