Honestly, this is likely a stalemate IMO. Ben is probably too durable for Riot to seriously harm, based on feats like 2:13 on here:
He's also taken spinning helicopter rotor blades to the face, multi-storey falls, impacts with speeding trucks etc. without any damage whatsoever.
However, as also mentioned by others, he is rather slow, and had trouble dealing with Reed during their brief fight in the first film due to the latter's flexibility, which Riot also has. So, he is probably going to struggle to land clean hits.
Hmm, Ben is actually a bit faster on his feet than I initially remembered, based on 0:38 here:
Obviously still slower than a symbiote though.