Tough... They kind of all have things I think the others are missing, if that makes sense.
Hoechlin's warm, friendly and down to earth. He has a genuine breeziness and ease to him which is great, but lacks a certain mystique, authority and wow factor. He's also the one who seems the most comfortable and least posey in his suit.
Cavill has the wow factor and the masculinity, if you will. He has the best physicality of this crop, in terms of selling fight scenes. But he lacks the other areas for me (with certain scenes being exceptions) and is a little stiff, largely missing the friendly nature of Hoechlin. He comes across as trying to hard to be calm and 'soothing'... But when he got to have a little fun (a couple of scenes in MoS, several good moments in JL) he does well. I'd like to see more of that version of him.
Routh's (KC, specifically) was self-assured, charming and felt like a real veteran and leader... He almost managed to blend the above two, feeling the most like capital 'S' Superman, yet also felt the most like a caricature out the three. That could partly be down to the comparative lack of screentime, I don't know.
Welling (Crisis, specifically) I thought did a great job with his scene-- arguably the best of the episodes so far, along with 90's Flash big scene-- but I don't know if there's anything there that stands out to me specifically. He was cool and confident as a veteran Superman should be, but also well and truly over it... which, while well performed, isn't something that I need in my ideal Superman.