Oh yeah, Altuve has a .990 fielding%, which is above the league average at 2nd base (.984). I don't know why he has a bad reputation as a fielder because every year, he's had above average, to way above average fielding% at second base. And up until last year, he had above average range too.
And while both Donaldson and Altuve are improving every year,Donaldson is 30 and has probably reached his ceiling.
Altuve is 26 and is entering his prime.
And I'm a walks guy, but I think you can be excused for his lack of walks because he is batting .340. Besides, it's not like he's Tim Anderson (8 walks, 90 Ks).
Maybe someone can put a side by side of their stats, but they are really similar on offense (Altuve a 162 OPS+, Donaldson 158 OPS+) but I'll take Altuve because of his base running and base stealing abilities, and his offensive output as a 2nd basemen, which you don't see much.