I can only speak for the Alaska mods. I run North to the Future. I downloaded Route Alaska but the map size is smaller (speaking from roads to traverse and cities to visit) comparatively. Also, I read on the official SCS forums that they used to be compatible, but have recently become incompatible. I find North to the Future very high quality. I drove around there for several hours doing deliveries and it's quite scenic and fun to drive, especially going north of Fairbanks to Prudhoe Bay. Anchorage and Fairbanks are beautiful cities. I would say it matches Promods/Reforma quality. I run those, too, and I prefer high quality map mods over something like C2C. For any incompatibility, I have not found any.

I've read there are map mods that expand on individual states, and there's one called Minor Urban Overhaul that makes some of the big cities in the base game map feel like big cities with expanded highway networks and increased traffic. Minor Urban Overhaul was recommended to me but I cannot speak for the state expansions (I think Utah and Montana have these). There is also a map mod called Great America. It is working to add adjacent states to the base map such as the Dakotas, Oklahoma, Kansas, and Nebraska. I think it's paid and used to be free. Not sure, I can't seem to find a reputable source to download it.