I really like the 2 Exist brand.
http://bananarepublic.gap.com/browse/product.do?cid=47081&vid=1&pid=637911022In stores they're 25% off for 3 and it's stackable with 40% savings, etc.
Hanes has an extra soft type that's worth checking out IMO
they turn grey quickly. though there so soft! i have themi have an issue with the yellow under the arms. i dont believe in spending money on good expensive undershirts bec of this issue, so instead i buy hanes 4 for 13 and change every 3-5 months ill buy new packs. i need like under armor, but there 30 a piece
well, depends on your budget. calida is amazing but high price.I tried every [almost] v-t and settled on landsend and tiger mountain. both are extraordinary quality and reasonable priced. tiger mountain is a bit more heavy though
I found Zimmerli of Switzerland to be quite comfortable.