Just bought a couple t shirts this weekend based on a couple of your recommendations. Here are my impressions on what I tried:
1. Urban Outfitters - The BDG cotton/poly t shirts are very nice and soft. I went ahead and bought a size medium for $14 (it's a pretty good slim fit, tad long but hopefully it will shrink in length when I wash it).
2. RevolveClothing - I picked up two Alternative Apparel eco-heather t shirts in size medium and large. Being a 1st time customer and using the 15% discount, I was able to get each shirt for $14 a piece. I love the feel of these shirts - they feel soft, yet sturdy (the collar doesn't seem like it will stretch). Size wise, I decided to keep the large and return the medium, as the chest/lat area was too tight. The fit of the size large is very similar to the BDG size medium.
3.Gap- They've improved their t-shirts since the last time I bought something from them two years ago. The fabric is much softer than I remembered them to be, and they do have a nice selection of colors available. Nice shirts, but the fitment of the shirts are kind of off (the sleeves are too wide in diameter in proportion to the sleeve length).
4. Pacific Sunwear Outlet - I picked up two solid colored Zoo York t shirts ($7 each) that also feel very soft and have similar fits to the BDG/Alternative Apparel. The size large fits me nice in the chest/arms, but the length is considerably longer than the BDG/American Apparel (I'll have them shortened for $5 a pop). These are a very good bang for the buck, but I still feel that the alternative apparel has a slightly better construction.
5. Target - Saw a few threads about the "Merona" t-shirts from Target, so I decided to see if they were as good as people proclaimed them to be. I found them to be sized bigger than the other aforementioned brands (the size medium was a bit loose) and not as soft. Sicne the cut of the shirt wasn't flattering, I decided to pass.
Conclusion: My two favorites are the BDG/Alternative Apparel. I'd probably pick up some more zoo york shirts if they are on sale again (for $7 +$5 tailoring =$12 for a good fitting tshirt).