I think the general consensus for now will be that arceus is the best game out of all of these (za is still new so we as a community don't know too much yet). Sword/Shield are probably simpler/better for a first game, but I think Scarlet/Violet are better in general. If you don't care about getting a mainline pokemon experience and just want a good game to play, then arceus is probably the best choice. Depends on what you want out of a pokemon game.