The first mare is in foal.. So, if you don't want a foal, I wouldn't get her.. especailly if you haven't had one before.
The second one looks very underweight to me... well, not nessecarily pony but just too thin.. he also has a bit of a swayback..
The third mare looks kind of ribby, but it's a bad pic so I can't see. Are TBs uaully built like this? (I'm not very familiar with them.. Our barn has only ever had two and one was only there for a month) She definitely looks under-muscled, too.. :\ Also, you've said you were using them for jumpers, eventing, XC.. it says she's a dressage horse, better on flat, so.. :\
I like the last one as you can continue to train her into whatever you like..