Heather seems to be the best bet IME. I bought a 3 pack of gray PRL heather v necks at TJ Maxx the other day for $15. They are quite soft and are a nice shade of heather that is a lighter than what I think of when traditional heather comes to mind.
I've also made my own deeper v necks out of crew necks with a steady hand and some scissors. I find, especially in the event of wearing BF sport shirts, the average v neck can peek out from time to time. Although they garner no style points and they can look quite rudimentary, the point of the undershirt (IMO) is to provide comfort while not being seen; and this tactic is quite effective.
I've also made my own deeper v necks out of crew necks with a steady hand and some scissors. I find, especially in the event of wearing BF sport shirts, the average v neck can peek out from time to time. Although they garner no style points and they can look quite rudimentary, the point of the undershirt (IMO) is to provide comfort while not being seen; and this tactic is quite effective.
