So, I'm a firm backer of speed. Its hard to get around.
That being said, Superman is not particularly smart nor skilled at combat. If he gets hit by Stormbreaker, he's done for. We have seen electricity does effect Clark and will slow him down and that's much weaker electricity than what Thor is putting out by a longshot.
If he tries to do what he did to Steppenwolf to Thor he gets one shot. If he doesent use his speed from the get go he gets slaughtered.
Superstatue force Superman (which we have seen him use twice out of three movies) should win.
Also, both Jane and Thor got an increase in speed though he can still statue them to some degree.
I'm gonna say split, sheer speed is a mfer. Clark's own intelligence and lack of tactics negates a good portion of his speed though. If he tries to use hv he is also going to screw himself as we have seen that he not only has to charge up, he has to remain still while doing so. Leaving him open to multiple attacks and his hv isn't going to kill or even injure Thor without prolonged exposure. Something he does not have time for.
Split 5/5
I am under assumption both Jane and Cap have Thor 1 or A1 level stats.