Im surprised this many people answered. I figured we would all be too busy repairing our RV's, wishing we had the old Eureka back . :)
Welcome aboard , many good people here will be very helpful to you as you get into it.
Research dealerships for a reputable one that will be there "after the sale".
I found it easiest to buy from a dealer who i planned to return to for warranty work. It certainly always saved me time because i got repair appointments quickly and built lasting friendships that went beyond warranties.
Pick your desired floor plan for your needs.
I would buy 'any brand' if I had the things above. A good dealer will repair it and they are ALL repairable.
I would have a queen island bed, that you walk around to make it. It's much easier for you.
Bunks for the kids, there are models with 3 bunks. Try to keep it as light as possible. Watch your payload of the TV (tow vehicle).
To get a good idea of a TT's real loaded for a trip tongue weight. Take 10-15% of the trailers gross weight rating and use that as a basic guide. Make sure you have enough truck to do the job.
When you look at trailers, sit inside them and role play. Spend a lot of time inside it and feel it out, move around as if you are using it.
There will be times when you will have to be inside as a family during inclement weather.
See if it fits your family. See if the dog likes it . If not , you'll find out that those RV carbon monoxide detectors are also methane detectors. (and the dog will let you know at 3 A.M. )