Franklin's nature makes him a bad opponent. Anyone strong enough to really be a threat likely shows up on his precog and he preemptively prepares for them and has countershields in place that will outlast the ending of the universe or basically unleashes an ultimate nullifier blast at his opponent and erases them from existence. RKT is definitely top tier. I'd put him above Odin. But against someone who can casually turn reality into play-doh is not something very many can contend with.