The frequent Fflyers may have favourites, however in my (admittedly relatively limited) experience, they’re all great if it’s not your usual class of travel.

If you’re travelling with someone, the buddy seats on the A380 and (IIRC) the unrefurbished 777s are good fun. I’ve not tried the new suites with doors, but the seats are materially the same. I sadly never got to fly F on a 747, which is a shame. I would just go for convenience and price.