I believe that it was the old, original OldSchool KO I'm thinking about right now but it whatever server it was, it was the best in my opinion.
It had everything, starting gear and lvl's and all you had to do from that point was farm armors. They had every single zone, boss zone, krowaz, bifrost, andin each a area you could farm for items or even PK there too. It made the server endlessly because new people constantly came therefore we always had to farm new items and the humans knew that so they'd always try and come kill us.
The upgrade rates were pretty fair from my memory and they only had 1 set of armor and weapons in the PUS and those didn't make you massively overpowered either. The server was running nice and strong but I had to quit due to work and stuff. When I returned, the server was gone because the OSKO I played recently is super slow XP/Hard farm and I don't have time for that these days.