best engine swap

i have a 2000 civic dx automatic. i was wondering what would be the best engine swap for this piece. i don't want to make it the most powerful thing in the world, but this engine doesn't cut it. i first want to get a new engine put in, switched over to standard.

this car won't be made for anything real heavy, just maybe some drivin fast and all :-D

i was considering swapping my d16 with a b16 or b18. however costs is what i am totally clueless about. around how much would you say would each of those cost and what would be the best swap ?