I think the first question to anwer for yourself is: How do you plan to use it? Will this be strictly car camping, strictly backpacking, or some combination?
The answer to that question will begin to tell you where to look. If you are car camping only, my theory is the bigger the better. Sure the big ones weigh a lot, but what do you care for 50' or so of carrying it?
For car camping, I use monster Target special, the brand is Eddie Bauer but I bought it at Target, that cost me about $120 or so. Have had it for 3 years, and hasn't leaked yet. Has fiberglass poles, and I've been in winds strong enough to blow it flat (it stands over 6' tall). The second the wind stopped, it stood right back up, no problems. Has deflected heavy rain, but I've never put it to the test in a seriously rainy situation. But for Colorado/Utah storms, which are violent but typically short, no problems. Having three rooms and three seperate doors has come in handy more than once. One year in Moab we made one room a garage for mtn. bikes, so they weren't so tempting when we left camp. Also nice to be able to stand up inside the tent.
If you're going smaller than that, but not down to backpacking only, my rule of thumb is to always buy one size bigger than you think you need. A 4 person tent barely fits 4 people. Add in bags, packs, clothes, etc.... and you get very crowded very quick, so for your needs I would go with a 6 person.
Weight and size aren't real issues (IMO) unless you're backpacking. At that point the whole equation changes.
So my personal lineup-
Eddie Bauer monster tent for car camping.
Eureka 4 person dome for solo car camping, or smaller situations.
REI 2 person back pack tent for backpacking. I forget the model, its been awhile. In fact, I'm not 100% sure where it is, probably wherever my backpack is.
No matter what size you decide on, key leak points are seams and floor. I always seal the seams when I buy a new tent. Most sporting goods stores will sell you some seam sealer, some tents even come with it. Easy to apply (do it outside) and seals all those needle holes on the seams.
For the floor, just get a cheap big tarp (assuming you're car camping). Tarp should ideally be just a tiny bit smaller than the footprint of the tent. Any part of the tarp that sticks out will be a water magnet, funneling water under the tent floor and typically right to your socks.
Hth.
-Matt