i heard j4 is quite underrated on top. i actually lost my promo because i was matched against some guy playing j4 top, he built pure ad and took teleport. he would gank bot and then tp top and deff turret, was a really pain. he was played as a tanky / support jungler as i remember. i played him a couple of times in jungle myself and didnt do well either. search some guides, they usually offer useful tips and tricks about champions.