Nothing wrong with that grey's bone. In fact it's more than sufficient for his body mass. He could easly be a couple of hundred pounds heavier and be fine on those legs.
HOWEVER. He appears quite heavy on the forehand in the flatwork pic. Haven't watched the videos.
The horse with very little video, I would avoid... if they bothered to TAKE video, why not take more? Get some better jumping vids? Is there something wrong? But his jumping form appears nice in the photos.
Top horse no way, jumping form is just dreadful and guaranteed that's a horse that knocks a lot of rails. Good job it's already sold.
I'm also looking for an eventer... out of the options you have posted, I think I like the grey best, but I don't much like him either. That neck is just... ick. It's ok in the standing "conformation" photo (which is really bad to judge confo off) but in the flatwork pic it's ewed and he's not using himself correctly.
I am not much a fan of Tekes as a whole, I do like a nice one (as in, bred specifically for eventing and therefore moves and jumps like an event horse) but on the whole I'm not especially enamoured of the breed.
I think constraining yourself to ONE breed is a bad idea... I'm looking at TB's, but that's because I don't have a huge amount of money to spend on a horse and the only cheap horses that are any good for eventing (here, at any decent level) are TB's and standardbreds... and I don't want a standie.
A CLEAN SLATE FOR THE FUTURE