so just because people dont play it its not viable? So when froggen picks an annie and destroys with her in challanger the champ suddenly becomes viable?or snoopeh beeing jungle malzahar?or ap nida+soraka botlane? :D
every toplaners job is to jump on the adc and burst it down as quick as you can, rengar is awsome at that just imagine the amount of damage from a full combo with shen proc after every skills :D
Zed in my opinion is a full damage champ, 0 def but awsome burst. I think hes good but for top there are much better options them him, hes a pretty darn good jungler/mid tho :)
to be honest with you the 3 champ you said is best in jungle or mid in case of kha, if you want to be a good toplaner i suggest pick the likes of shen, olaf, malphite, renekton, riven, zed :)
its stupid to store that much data in 1 file, 0 flexibility and hard editing i mean i tried to open it and eclipse freezed out with 768mb heap given :D