Yeah, 27 point buy is actually lower than the average results for the standard 4d6-drop-lowest method. 32 is much closer. (It's actually 33 and a bit, if I recall correctly.) So 27 doesn't seem fair to me. I foolishly gave my players 27 points right when we started playing 5E, before doing the math, and now I'm looking for an excuse to bump up their characters' scores a bit in-game.27 or 32 point buy.
I like more 32. 15 is still the max buy, but it has less "tanked" abilities.