If you're playing ELO, Wardom is better, IMO. Wardom is much more stable, and has an advantage in high-pill fights. Considering the fact that you have some nice DR, you can try to land Wardom on turns when his ability isn't active. That can be a good way to catch people off-guard.
XU52 is more suited for attempting KOs in a 12-life format.
I perfer XU52 because wardom is conditional. I belive that 5* in elo should be flexible and/or hit hard. Although Wardom has that very solid 8 power, he doesnt hit hard without his revenge. That being said though, u could argue that revenge is pretty easy 2 pull off, but i still like XU52, cuz he can nuke on any round.
Actually I tend to prefer Wardom in weeks where all GHEIST staples are unbanned. He maintains solid power and decent damage against fellow GHEIST, while XU52 struggles against cards like Dolly or Zero Dead pill for pill