Cooper's Discoverer and Michelin's LTX M/S (when marketed as OEM replacement) are targeted to the same market. Michelin's similar BF Goodrich Commercial T/A is probably a bit closer to the Cooper price point, as will be Firestone's Transforce and Goodyear's commercial Wrangler lines. You can go even cheaper with Cooper's commercial Mastercraft or Roadmaster lines, or any of number of branded imports. Or you can upgrade to Michelin XPS, Bridgestone Duravis, or something in Goodyear's R-series commercial lines.
One thing different about LTX in load range E, versus many lower cost OEM and replacement all-season LT tires in the same load range, is that the LTX gets an extra body ply. Other premium brands might have heavier belts, or Kevlar armor plies.
Different body construction, body weight, belt construction, tread thickness, tread designs all have an effect on durability, ride comfort, noise. But you don't find this out until you actually buy the tires and install them.
I tend to put my long-term relationships with my local tire dealers ahead of retail price points when choosing tires. I've run a lot of different Cooper models, different grades for different cars and trucks, because I had a great Cooper dealer who carried Michelin as his premium brand, Hankooks for price, Toyos for a performance market. Thus my minivan and SUV got Discoverers, sedans Trendsetters or Lifeliners, and the pickup I drove around town Mastercrafts replacing the cheap OEM Firestones.
But my Class C got Michelin all-steel XPS Rib to replace the OEM LTX M/S because I wanted an extra degree of tire carcass toughness for this "always fully loaded" application. It is probably overkill, the XPS is a tire body designed to have a long tread life and be retreadable a couple of times to get a couple hundred thousand miles over a ten year or longer life. What mattered to me was the design for a ten year or longer carcass life.
Since my Cooper dealer has switched to Bridgestone/Firestone as primary supplier, I face different choices for replacement tires. Should I ever wear out the XPS Ribs (unlikely at my age and RV usage) I could go to Bridgestone Duravis on the RV for hard use, or Firestone Transforce if I only do local trips.
If you plan to replace your RV tires every 3-5 years, as is often advised here, you might go with the cheaper tire models which will have lighter tire bodies and maybe less original tread. A tire with lighter tread will be less likely to throw the tread if you tend to run underinflated.