The previous info from Nikki is a little outdated. Merida is no longer by Small World but meets at the umbrella outside Fantasy Faire. The Evil Queen is no longer out except for extremely rare days, same for Hook (and he'll wander around if he is). Alice and the Mad hatter also wander around FL. Peter, if out, has been along the path toward the wishing well.
Your best bet for the shortest lines and most characters is Town Square. Mickey and friends are out most of the day with a few breaks, plus sometimes you can find Cruella, Mary and Bert or other rare characters, and they are usually out for 30-40 minutes at a time. Lines are usually 5-10 minutes and you can see a lot in a little time!
Is there anyone specific you are looking to see? Which days are you going?