top and mid work pretty well, would recommend watching an lcs game/pro replay of jayce helps you understand. He is a bursty champ in general with a very large mana consumption, which is somewhat compensated by the fact he can sustain it back by autoing in melee form. In top he is a massive lane bully because his range means he can poke melee champs very effectively, and if they engage on him he can outdamage almost everyone early since he has 6 abilities of damage, even if they are winning the trade he can disengage with his e in melee form and go back to farming/poking. In midgame his poke is very powerful, but requires good aim as it has a high cost, and doesn't pass through enemies meaning you can't afford to wiff to many shots. He can split push, but it isn't ideal because his ability to duel is very matchup dependant, falling off against tankier champions but retaining an edge against squishier ones. He provides nearly no utility and building tank items on him is pointless so you need to always be competitive in gold.