Magic is a beautiful ship and I LOVE it; in comparing the the Fantasy, a positive for the Magic is that, while neither of our cruises were at "peak" times, the Fantasy (and in particular the kids clubs) seemed so much busier because of the size of the ship. The Magic is smaller and more intimate. If it were just me, I would be perfectly happy with the Magic, but if it were only up to my kids - Fantasy Fantasy Fantasy. Bigger kids clubs (but not "bigger" enough to make up for the increase in cruisers), mid-ship detective agency, "cooler" Animator's Palate, magic porthole and, of course, the AQUADUCK.
Never been on the Dream, primarily because of the short duration of the cruises.
So in short, if it is just adults, I think that you will be more than satisfied with the Magic - and so will any kids. Especially since you will save a bunch of $$ going out of Texas. BUT, once you do go on the Fantasy with kids, it will be hard to get them to go back to the Magic (but my kids are going to have to suck it up, because our next cruise is on the Aquaduck-less Magic again)!