IMHO the 255/75 and 275/70 are perfect sizes for the 4R. I ran both on my '07 GX470, and came to favor the 255's.

Your usage sounds about like mine: no hardcore wheeling but forest roads, moderate trails, daily driving, and beach. I never had an issue airing down the 255's to ~15psi on the NC Outer Banks.

The 255's drive and handle well: you maintain great feel, they react quickly to inputs, and in my experience the narrower profile was much less likely to hydroplane than the 275's (or even 265/70r17's I also had).

That they're lighter and fit the spare location are significant bonuses.

Not going to comment on your brands due to inexperience with them, but I ran Cooper AT3's in 255 - they were terrible in every manner so I returned them for Hankook Dynapro ATm's. The Hankooks may have been the best all-round tire I ever ran, but the old design has been retired (and I'm not crazy about the new design). Now looking at Toyo Open Country AT in this size to replace near-new 265/75r17 BFG AT KO2's in Load C the previous owner installed.