Tyson would be a problem to any fighter and he could beat any fighter. Thats because of his stile and power but the logical take would favor Lewis.
Just because you lose a fight doesn't mean your prime is over. Lewis lost to Rahman in his prime..but came back to destroy him and beat Vitali...
Lewis. Think a prime vs prime fight between the 2 wouldn't have worked out too differently to the fight they actually had. Tyson would come out swinging and put Lewis on the defensive for a while. Then Lewis would get his jab going take over in the middle rounds and take him out late.