Leviatonn, hands down. He/s the best stop-all in the game and works in many more decks than XU52 because he's only 3 stars. Leviatonn, Bristone, Methane, Z3r0 D34d is a common half-deck and quite strong. If your other half has cards with lots of damage, you can swap Toro in for Methane and use the non-GHEST cards to create two hit KO's.
I used to like Leviatonn but then when i used him in Elo, it ussualy came down to stats and pillz, thats where six power and no extra help kinda throws you down. mabey my lucks been gone for too long but then a gain he is also very predictable. THink about you aint going to use him on a card with no ability or bonus(MOst people, stress on most). If you get him ussualy you want to use him on a good shot but thats just me. So yes XU52