The idea of "better" is pretty subjective. If you really like making custom projects you could go for a NTC conversion, but if you just want to get out and start driving go for the electric. I'm not too sure if there are any definite benefits of a converted NTC vs. the electric. I haven't looked around too much for conversions for the NTC, but with the electric version available there probably isn't a big market for that.
I am building a TC3 for indoor driving this winter and for me it made the most sense to go for the electric version.
EDIT: found this thread:
http://www.rc-monster.com/forum/showthread.php?t=8093 and this:
http://rc-drift.com/rc-drift-forum/i...p?topic=3436.0