I love playing on a small continents map. I think I'm just better at building maritime empires. 
Whenever I settle on large land masses I always get steamrolled by aggressive AI because I can't protect everything. 
But at sea I just keep churning out military ships and station cannons/artillery on my cities and it's smooth sailing from there.

I like playing on a larger Pangea type map. My naval game is pretty weak, so I like having a big land empire and then paying off all the city states to be solid allies. The only miliatry units I have are usually gifted by the city states which I put around my borders. After that I just do what I can to keep the other Civs happy and I generally don't worry about war too much. If I'm going for a domination victory, the larger map can complicate things, but it is nice to have some breathing room in the larger continents earlier in the game.

I think I like plain ol' continents type map the best, although I also like "fractals". Don't remember if that type is listed in the game but it's in the map editor.  

@StupidGamer Lately I've been playing with a large earth map. I do find that large continents make a diplomatic victory much easier. Civs are so spread out that they rarely hate you. All the Civs seem to like me and give great trading deals, even the really aggressive ones that are constantly fighting over Asia while I relax in South America. If I was on a smaller map, I guarantee those same Civs would hate my guts but instead they love me. Only problems is that it takes so long to travel anywhere and Barbarians are always spawning, even in the year 1920. So much unclaimed space that isn't worth getting.

I like the continents. I like the mix of islands and bigger landmasses.

Random because random is awesome.

Continents, although it's more interesting to pick random - different map types lead to different play styles. 
 
Earth map is too predictable, when you find out where you are you kind of know the geographic situation you are in and what you should be doing. 
Pangea is too dangerous with the aggressive AI when you're not going for domination. 
Islands is nice, but I usually don't tend to get many ships which is why I prefer continents. It puts pressure on me from the other civs on the same continent and it allows me to go towards both land and sea armies. It's pretty much the all-rounder map type.

A huge island map or random because I really like exploring and colonizing new lands.

Continents, cause if I play on earth I know the layout.