There's still a player base of around 100 players that like low rate close-to-official servers. They are fairly loyal and stick to one server, though, unless the server owner becomes too inactive or closes the server. There's more players like that in SEA but they prefer sticking to their local private server.
Most players want several customizations like autoloot, healer, warper and a bunch of skill updates that make WoE more fun. But the number of servers that offer this are just as large.
What kind of RO server I'd love the most? Well such a server can't exist. But I want the times back of when I started to play euRO. So zero customization and still a huge playerbase and most players were not just elitist power levelers but a lot of role players too and people that just like to explore the world.
If I have a very close to official servers and find a friend that doesn't know RO yet and wants to try it with me, I can partially revive that feeling, though.
Other than that, if someone came up with an amazing customization idea, I'd also be inclined to try that server, because I'm kinda tired of pre-renewal 13.2. Always same spawns and same monster imbalances that cause to level on the same boring maps every time.
Some servers attempted a higher customization by now, but often it were just a bunch of skill changes where I only found 50% reasonable and the other 50% felt like "Oh the server owner really likes that class" or "Oh the server owner doesn't like this class".