I have this Dewalt XRP drill and I like it a lot, it has lasted a long time and has enough power for most anything I need. It's not too lightweight, though. A friend of mine swears by his Festool cordless drill. They are a bit pricey, but it might be worth it if you are doing a lot of work with a drill. I haven't used one, but it looks lightweight and has good reviews.

Festool Drill:


Edit: fixed link and added image