I've been out of the new/gently used RV market for a while, but do some research.
It used to be that nearly all RVs were constructed with 2x2 wood studs with a luan panel inside and aluminum or fiberglass outside. Once it leaked, it was a bugger to fix rot. Fortunately nowadays there are several options out there with aluminum studs and laminated foam insulation. The walls are kinda one big stressed-skin. Very rigid and if you have a leak the most you would have to do is replace a bit of interior paneling.
Back in the day, the hot ticket was a Holiday Rambler; aluminum studs, smooth aluminum skin, and a 2-piece aluminum roof. No maintenance like a rubber roof, rarely leaks, super nice interior. But, you have to go back to the mid-90s to find one before Monaco bought them and it all went downhill.
The late 90s - mid 2000s were a pretty dark time for RVs. The market was flooded with super cheap junk that was slapped together for the lightest possible combination. That led to luan cabinetry, carpet that lasted about 2 seasons, and slide rooms that leaked and only worked a few times before the gearbox exploded or it came off the track. Many of them also tried to cram as much faux luxury into it as possible which (in my opinion) has no place in an RV. I don't mind luxury things, but I ripped up the carpet in my 92 Holiday Rambler and replaced it with linoleum. Keep a broom around and cleaning up after a rainy day of tracking in dirt and grass becomes super simple. RVs are so "close" to the outdoors that I prefer to lean toward RVs that have durable fabrics, hard floors, and functional space. YMMV.
Unless you really need it for space, skip the slide room unless you really check it out. Most motorhomes have the "good" kind that just go straight out. Many TTs and 5ers have "flush floor" slide rooms where the box goes out and down. Complex mechanisms and they are more prone to leak, let in vermin, and mechanically fail. If you have one that just goes straight out and straight in, it's a better bet. Do your homework, though. The majority of slide rooms are just stoopid. My friends have a lovely double-slide 5th wheel. With the slide rooms in, you can't access the fridge OR the bathroom. Really kills the idea of stopping by the road for lunch or a pee break. If I buy a slide room, I will ONLY buy it if the RV retains full function of everything with the slide(s) retracted. Also avoid slides with plumbing or appliances in the slide room. That means gas lines, drains, electrical, water, etc have to have motion and flex.
My newest 5er has two slides. It's a rear kitchen, so the big slide in the back has the couch and dining table. It does have electrical outlets in the slide, but if they fail the only thing I can't do is use the outlet until I fix it. If your fridge is in the slide and you lose electric, you will be throwing away food. The other slide is in the front bedroom, and they were even thoughtful enough to not put things like drawers or cabinets where the bed would block them when retracted. Nice touch. Full function with the slides in or out.
I also strongly suggest against an automatic awning. To properly function, an awning must have either a significant slope, or one side lower than the other. Otherwise it will belly with water and either rip itself off, or rip off the whole wall of your RV. Automatic awnings often have a kinda complex set of sensors that keep tabs on how much weight is in the awning as it fills with water and retracts itself to dump the water... all over your patio. Then you also have the problem of a failure point or loss of power where the awning doesn't retract to dump water, and then see the "rip the wall off your RV" part above. My manual awning takes 30 seconds to set up, and I simply put the rear support two holes lower than the front. It stays up all summer and drains itself nicely.