Pretty broad question.... you're likely to just get, "I like brand X because I own one and it's the best." Or, "I own brand Y and a hinge screw came loose so stay far far away from them."
IMO, all of the mainstream brands at a given price point can/do turn out great trailers but sometimes churn out a lemon. Rather than shopping by brand I usually shop by floor plan, weight, length, etc. and then go from there.
Mainstream brands I consider things like Keystone, Jayco and Forest River
Next step up would be Arctic Fox, Grand Design, Open Range and probably a bunch of others I'm forgetting.
I actually just bought a new unit over the weekend after doing months of research and now I don't know what to do with my time. Spend lots of hours looking over manufacturer's websites for floor plans and on internet forums. That's the best way I've found over the years to make a good choice.