My newest 260 brass is Lapua, but I'll just hold it till the R-P brass is at end-of-life. My Tikka shoots great with the R-P brass, which is highly prepped. If I didn't reload, I doubt that I'd have a 260. But...I do reload, and I shoot that 260 a lot. These days I'm using the 100 gr Nosler BT over 41.1 gr of IMR4064. That's close to max, so work up to it if you plan to try it in your rifle.
I had some Nosler brass till it started splitting necks. The Nosler is great brass, but doesn't seem to last as long as Norma and Lapua. If I had to pick between Norma and Lapua, I wouldn't choose. Either will do equally well, in my opinion and experience.
And perhaps I should mention that my rebarrelled 223, with match chamber, would not chamber a loaded round with Lapua brass. The case neck walls were the problem, being too thick. That came as a big surprise. I'm having the chamber neck opened up a bit, rather than turn the necks on a bazillion cases. If you get some new Lapua brass, and you have a match chamber, I suggest that you measure loaded rounds to be sure they have room when chambered.