Several points that have to be considered:
1. budget - Motorhomes cost more and can be more costly to maintain. If you don't have to worry about costs, and you really want to try owning a motorhome, go for it. Consider also that you will probably want to tow a car so you don't have to take the motorhome with you when sightseeing or running for supplies.
2. tow vehicle - If going with a TT or FW, the tow vehicle can serve as a second vehicle. Of course, it's not going to have great gas mileage.
3. storage cost- If you cannot keep your RV on your property consider storage cost which is often based upon total length.
4. ease of maintenance - We downsized from a 29' TT to our slightly shorter (26'9") Minnie and when it comes to washing & waxing and maintaining the roof, it's all I want. As I get older, I don't want to maintain a large FW or motorhome, and also with our budget, we'd rather spend the $$ traveling.
5. ease of navigation - The larger the unit, the more challenges you can have navigating "tight" gas stations, city streets, etc. Also, longer units may restrict your choice of campsites. Whether camping at private of public campgrounds can make a big difference with this, and also if you typically plan a trip and make reservations ahead of time.
6. Buying used may be advisable if you're not sure what you want to do. That way, if you decide you want a smaller/larger or different type of RV, you can minimize any financial loss.
Bottom line....take your time and look at all the options that are out there. Balance the "wow" factor of larger, fancier RVs with how much and how you plan to use it i.e. if you're going to use it for a full time residence for half the year or so, you'll want to go larger (FW or motorhome). If you're going to use it for a lot of shorter trips or even trips of a couple months, you can get by with smaller, depending on your needs and lifestyle.
Good luck, and I hope you're on the road and having fun real soon!!
Honest disclosure: If money were no object, I'd love a nice coach for longer trips and I'd have a really nice hybrid for when I want to enjoy a more tent like camping experience.