Ugh...my vote is between Absolute Zero and Gaia... >_<;;
Absolute Zero is fun if you work it with a pure E-Hero deck and have Terra Firma out with it at the same time. XD
Gaia is handy when you can't beat over certain monsters...again, fun with Terra Firma out at the same time. XD
...Sheesh, everything is fun when Terra Firma is out (in my opinion). XD