As someone who lived in NH for many years, I'd say NJ is not in the northeast - closer to mid-Atlantic ;-)... Beyond that is it your son's desire for being 2-3 hours away or the parents desire? The short answer / assumption I have for your basic question is TX baseball will be deeper than NJ.
Anyway - here's a perspective for you as a parent of NH players and having umpired games at the "better" and "larger division" HS schools... I've seen HS baseball in NH, NC, and FL - the biggest difference I've found is rosters in warmer climates are much deeper for the better schools. Let's say for NH it was 3-4 players deep, NC was 5-6 deep and in FL 7-8 deep. That is good hitters up and down - they've seen a lot of baseball and play year round. One my sons was an effective, but not top level pitcher in NH that went to a D3 in PA - he was mid 80's FB. He did OK, wasn't dominant, could pitch outs (if only the fielders would make the plays - that's a different story). Another son again not top level, but was able to get his FB to upper 80's ended up at a D2 school in NC and quickly found that batters in D2 will hit a straight fastball a long freaking way. Watching the D3 games - the better teams had deep rosters, but still lots of "holes"... Watching the D2 games there were much fewer "holes".
So what's the moral here? It's all about perspective and being realistic. You now have a map of the schools - go make visits. Do your own comparison. What type of school / division do you play in NJ - the answer doesn't matter, but understand the comparison you need to make. Consider is it 'more important' to be on a roster of a mediocre team and get to play or be on roster of a good team and possibly never see the field? Oh and of course, don't forget the broken leg test - will you be happy at the school if you get injured and cannot play.
I think if you follow along long enough here - you'll read that when players that go top D1 and don't get the play time they want or feel they deserve, they will transfer to either a lower D1 or a D2 or a D3 school. That transfer may include a trip thru some juco, some naia, etc. type school. If you're a coach there, that player is coming for a reason and will take the roster spot of someone else. Oh and those players want to go to the top lower level school because they feel they would be the "king of the hill" there. They may not be, but that's something the coach will need to figure out and ego wise they may not necessarily like bringing in a player, finding out he's worse than what he has, and then sitting that player - makes 'em look bad.
Good luck with the decision! I hope you get to see some baseball in TX and can/will report back here what you find.