You may as well ask, "How high is up?" There are many, many, floorplans and manufacturers of trailers and no one can advise you on which is best for you. I am not familiar with your tow vehicle but you do need to research how much you can safely tow after you load your TV with everything including passengers. Then get yourself to an RV show and check out what is being offered. You could also just go to different dealers and accomplish the same thing but at an RV show they are all in one place. The advice to leave your wallet at home is great advice. Decide how many slide-outs, if any you need. Check out the layout of the different kitchens and find out which works best for how you use it. Make sure the bathroom is usable and there is sufficient space to take a shower or use the toilet. Check out the size of the holding tanks and determine if they are big enough for the way you will be camping. Understand you need to consider both outside living of the TT as well as how space would be used when you hit a rainy patch and everyone is cooped up inside. All of these wants and needs will be dictated by the size of your budget and the capability of your Tow Vehicle. You also have to budget for setting up your TV to tow whatever you buy. You will likely need a trailer brake and a weight distribution/anti-sway hitch.
This is the fun part. Do your research and find out what works for you and your family. There is no one perfect TT or one best manufacturer, but there is one that is best for you. You just have to go find it.