Much of how stable a travel trailer is depends on what is towing it. I think (moreso than a fifth wheel) too often large travel trailers are being pulled behind trucks that are inadequate for what's being pulled. Again, the salesman telling a new buyer "you can pull anything on the lot" is where it starts. Then an improperly set up hitch, an inexperienced driver, excessive speed, and a 35 mph crosswind and several semi passes later, the travel trailer gets written off as an unsafe death trap.
I pull a 30' TT. With my old 1989 F250, it was a handful at times, especially in high wind. My 2014 Ram 2500 Crew Cab Cummins barely knows it's back there. I keep it at 55 MPH, and have yet to have a white knuckle moment with this setup. I had to pull it back from Ruidoso in 25-30 mph winds a while back and it behaved just fine. That said, if it gets much windier than that, ANY RV should be parked until it calms down.
Find a floor plan (TT or fiver) that you like best, and buy it. Ensure you have enough vehicle to pull it, set it up right, don't tow in crazy wind, and keep the speeds down. All will be fine.