variant
Adventurer
This is a good idea, I feel -- giving choice allows design flexibility, and making it a feature of a starting character rather than of class or background makes sense. I would like to see some kind of constraint imposed, though, so that it actually is a choice between equally reasonable options, and not (as you noted in January) something where selecting Dex/Wis is disproportionately advantageous.
One constraint would be to offer a choice of pairs:
(a) Con and Str
(b) Cha and Wis
(c) Dex and Int
(for example; assuming the current imbalance is preserved in the final game, and I see no indications that it might change).
Another possible constraint (which I might actually prefer) is that you can choose two stats, but they cannot be your numerically highest ability (and if you start with two abilities tied at the top, you can choose neither of them). While mechanically I find this clean, the in-game narrative rationale will be a challenge for some.
If Strength, Charisma, and Intelligence aren't going to balanced with the other three, I think paired choices might be a better solution than choosing any two you want. The pairs you made are a good example of stats that are related to each other in some fashion despite being independent of each other.