It would be easier for people to answer your question with more info. Average range game will be taken. Age & gender of shooter. Etc.... I vote 7-08 but I own one.
There is very little difference. 6.5mm vs. 7mm, same case capacity. The 260 will launch a lighter bullet faster. The 7mm will launch a heavier bullet slower.
Mine is a 7mm08. I handload 120gr. bullets that will group under an inch all day. Accuracy is the key, any bullet will do if properly placed.....
I had to make that choice when I bought my son a Model 7 about 10 years ago. I went with the 7mm08 because I don't think the .260 is going to make it. Think about it. How many people do you know that owns one and how often do you hear about that caliber? For me the answers are none and not very often.
I think in a few years finding ammo will be about like finding it for a .357 Maximum.....not impossible but costly.