Is there an advantage to NTTA, EZTag or TXTag over the others? Will be driving in both Austin and Fort Worth areas, and occasionally Houston. If all 3 are accepted do you get the discounts for NTTA if you have a TXtag etc? I see the TXtag discount on Austin roads is much less than the NTTA discount on Dallas roads so I wondered how that works. I assume you can purchase any of them if you have a TX license plate?