I keep coming to the problem Saitama never gets to show his full power...
Strength- All 3 have displayed Hulk level strength... As such each is awarded 2 points.
Speed- Billy moves 1/3 of light speed in a Sprint pace, Gladiator managed to utterly defeat Hyperion in a nanosecond, Saitama lazily dodged lasers... Another 3 way tie.
Durability- Nothing here to indicate how durable Saitama is as he hasn't been really taxed by anything. Shazam similarly only occasionally takes strikes from top tiers like Superman. Gladiator was able to get back up after a strike that was powerful enough to catapult someone from the Earth to the Sun (Sol), about 8 light-minutes away. I give Kalllark the top position, and tie Billy and Saitama for this reason.