I haven't seen many 715T daughters. I had 3 bulls out of him last year and I really liked them and I've heard 715T's daughters are better then his sons. I have one 715T heifer right now that is 7 months old out of one of my top cows so I'll probably keep her for a replacement and haven't figured out what I'll breed her to yet. I haven't seen any Watchman daughters but have seen a few bulls. Deep soggy type bulls. I do have a couple Kruggerand bred heifers and one of them might be the best female I've raised in awhile. Super confirmation, pretty easy keeping, udder looks like it will be fantastic, and feet seem to be good although I might give her a touch more bone and a little bigger foot, but that's being nit picky.
So I'd say Watchman or Kruggerand would be a pretty good choice to go on those 715T daughters. A couple other ones I'd throw out there that I've seen awesome females out of are JBOB 4665M and TAU Grid Topper 43T - AMGV1036179.