Sorry... I was thinking of the 300 RUM from another thread
Of the ones you mention, I would pick the 300 WSM
. The 7 ultra will have better ballistics, but by the time you develop a good LR load and work out any bugs and get some good practice, your barrel will probably be toast or close to it. The 300 WSM will have very good barrel life if you take care of it. One competitor won a match with one that had 4000 rounds down the tube. You can expect 1000 - 2000 from a 7 RM or 300 WM and less than 1000 from a 7 Ultra.
With the 300 WSM, I would opt for a Sub MOA Vanguard. There are going to be some guys who like the Savage and I have never shot one so i cant knock them, but I have handled both the Savage and the Vanguard and I like the Vanguard better based on that limited experience. I also have S&W M1500 in 7 RM which is made by Howa, which also makes the Vanguards, and i really like it. It's very smooth, well built and the trigger was a breeze to adjust. It's very crisp and set to about 1 lb and it's a tack driver - 28 years old and sub .5 MOA in a walnut stock shooting Nosler partitons the last time I shot it last year.