I like the third choice out of all of them. I saw she was a bit fiesty in the alley but hey, not all of them are dead heads. I bet she likes her job and just gets excited.
But overall, I think she's your best buy. You already KNOW her potential and have seen her run and her running style. She looked a little bouncy on her turns but that could just be her.
$7500 for a 1D-2D consistent barrel horse is quite a steal! Go get her! Fast, talented, proven, and pretty to boot. Heck, if I had a way to get her to OK, I'd be goin' and gettin' her.