Carnage might be worth it for TU value alone (his red, championed, is the best baking TU in the game), but probably isn’t, otherwise.
Nova and Miles are great.
Antman is very good, but a bit slow.
I like X-23 and Flaptain, but maybe a hair below those three (though, for various reasons, I actually championed both before Antman. And I still haven’t championed Nova, unfortunately).
Kingpin? I’d definitely put him below Nova and Miles, but he is very good.
Ghost Rider and Venom? Neither is bad, but neither should be a high priority.
if I understand it correctly, TUs scale the the recipient’s roster. so unless you’re sending carnage to a 3* player, not much reason to level him for that. my 4* TUs I receive are generally 328, which is the average of my t3. let me know if I’m off-base on that.