I'd rather PotD than FATE grind tbh. i feel like FATEs should never be the "best" exp at any level and should be something you do if you're nearby or for an achievement or optional sidequests. PotD definitely needs more variety tho - I hope if there are any future iterations of deep dungeon they give randomized objectives per floor (like Nyzul yes) so as to change things up with each time you run it.