Honestly it really doesn’t matter, whatever you like to play will be the best class to you. I personally like HU, but RA is fun to play too, and it’s always good to play as a FO (even tho I suck in this class)
id say try em all and gather items, learn enemy movements, and watch spawns. cuz honestly that’ll make you a better player, but most importantly enjoy the game for what it is.
but back to solo question if that’s the way you wanna play the game then do you man, i personally think the more the merrier.