Personally, I wouldn't buy these for registration fee...
I do not know what iTopBest means, or even what it is targeting and LowVegasTickets in that people do not search for Low, preferring to add the word Price or Priced.
Having said that, the second is definitely the superior of the two but will it be worth your time emailing anyone?
Low-mid $xx for LowVegasTickets.com