I won't say "best" as there is no such thing.
There is best value, there is best supported and there is best for the job.
We have sold aa large number of the 700 XCR Tacticals and had really great feedback from clients. In my OPINION the stock on the 5R and Sendero is bulky and not the best suited for fit, the XCR Tactical seems to me to be a better fitting stock.
1 person posted 300 RUM, the problem is that high quality brass is extremely hard to find and that the barrel life is significantly shorter than the 300 Win Mag offers.
Another posted 300Wby, good brass is certainly available, but Wby rifles are not renowned for their accuracy due the the tremendous amount of free bore they employ.
Of the assorted brands Remington wins hands down for upgrade-ability.
As for their extractor, in the 35 years I have been in this industry I think I may have replace 20 of them. They work pretty reliably on the whole.