1) It depends, but I have a very hard-to-fit TB (not necessarily tall withers, but LONG withers). Out of everything I tried, the two MT saddles I put on him fit him the best (Premia M tree and Laura B Genesis [adjustable] tree).
2) I ended up buying the Laura B, and I LOVE it. It's very comfortable, and everyone who has sat in my saddle agrees!
3) Like I said, I tried the Premia and Laura B. The Premia was comfortable, but I didn't feel like it was anything to write home about. The Laura B is great.
If I might make a suggestion: Visit Classic Saddlery - Quality English Horse Tack & Horse Supplies for the Equestrian.
and talk to Lynnda. I found a recommendation on here for them, and I am SO glad I called her! She was incredibly helpful at talking to me about my horse and myself, and from there she was able to make a good suggestion for me. Plus she has a lot of clearance MT saddles that were samples and such, so they're brand new for a great price!
Something else to note: I use my saddle with a Thinline half pad. Since I don't have the budget for a custom-fit saddle, this pad gives me a little extra peace of mind. It's a great pad. I absolutely love it!