Leaning towards 1.Nautilus 2.Zac pre rework 3. Malphite 4. Shen
Now I'm mostly a adc main and only go top lane to play Fiiora or yasuo, and I'm trying out new champions to expand diversity in other lanes, my playstyle is usually kiting, going all In, while also protecting the carry.
Shen is really good at protection. He dashes in and dives into the fight while taunting, which can grab attention from the add, but he's somewhat weak in lane.
Zac has good tools, but I frankly see him more in support than top lane when not played in jungle.
Malphite has some pretty good cheese with his ultimate and cc. Ganking a, friendly Malphite's lane is pretty easy, especially of he's pushed up since he has some decent anti-escape tools.
Nautilus is an odd, off-top pick that has high mana costs. You'll most likely be buying a righteous glory, frozen heart, or iceborn gauntlet if you're ahead.
I personally prefer juggernauts played super tanky, like Garen or Volibear,but Cho'gath is another good option of you're low elo. Out of the four you mentioned I'd pick Malphite or Shen on that order.
