Out There is my favourite Dinosaur Jr song, otherwise stuff from the first three albums is usually your best bet (Little Fury Things, Freak Scene, Yeah We Know, Keep The Glove)...
Where You Been?, Without A Sound, and You're Living All Over Me are pretty good albums.
Beyond, their latest, is my favorite, though.
Their second album, You're Living All Over Me, is their best. Bug (the third album) is probably more accessible though. They're both essential albums anyway, so you should own both! Their new album "Beyond" is great as well.

I was lucky enough to see them last month. They were fecking awesome.