In a somewhat order, but not 100% accurate.
NamelessRO Sunrise (low rate) - First RO server, played there a while
EternalRO - Server closed 2 days after I joined
ShadowRO - Played for many years while also playing some other servers. Found a Lady Tanee Card and Incancation Samurai Card there, both at 0.05%. The server also started based on the Freya emulator, eventually we switched to eAthena. Server started going downhill slowly afterwards.
FaithRO - Fun server, I first played it with my cousin, used his friend's hunter account to hunt stuff, then I eventually made my own characters. Found a Deviling Card there at 0.08%.
ProjectRageRO - Found my first MVP card there (Eddga). Also found an RSX Card later (I was sad), both at 0.10%
RaptureRO - v2 of ProjectRageRO. My cousin and I found a Kiel Card there at 0.03%.
Destina - I loved the scripts there (treasure chest sand thing, that scripted event where you needed to chase that Cat o' Nine Tail, etc)
PhoenixRO - That random PK mode thing for 15 min was fun (and messy in high end MVP places)
AdventRO - I think it was that server where the losing guild quit the server after losing the first WoE. Server died after that. Quite sad... (we did mi gao duplication to lvl up, so that was their excuse)
PumpkinRO - Mainly BG'd there with a clown or pally, and had fun in WoE. And hunting hats...Whisper mask...It still haunts me. (had to kill 2250 Porings to get a hat at random, and one of them was that)
UtopiaRO v1-2 - I liked the 30 min buffs there, and hunting for hats. Hunting the Bounty monster was also fun
LimitlessRO - The only thing I remember about this is the house system and being lazy to hunt a Green Ferus Card...
MalevolentRO - mid rate, was fun to BG there, kinda stopped when WoE came around
EternityRO - I only played there to help some friends WoE on one of their Paladins for the g18 or something guild, I forgot the name.
PortalRO - played there a while, v2 of ShadowRO. Found a Dracula Card there at 0.05%
FlawlessRO - unlike its name, it was very flawed and buggy. I'm surprised it even got the population it did (peak was 650 in around 2~3 months of uptime and it was a low rate, but there was no server protection (no harmony/ddos protection) and lots of bots. We also got DDoS'd. Once Harmony was put, lots of people were having issues getting the game to work, and no more bots, so population went down fast.) I also found a Kiel Card there at 0.02% and it was the last MVP Card I've found.
StandardRO
TalonRO - Played until Lv70, when autoloot stopped working, something was very demotivating in that server for me. Perhaps I just wasn't into RO much that time)
PureRO - The one server that I played for some time where I didn't make a million characters.
EvolveRO - I'm surprised we successfully camped Wounded Morroc for so long in there, nice server with good population, while it lasted...
SanctityRO - Somewhat mid rate, didn't play much...
AthereaRO - Nice community, but poor management, so it died
NanashiRO - Bad management. Lots of played complained after we killed Wounded Morroc, Bios, Randgris and Beelzebub (Beelzebub that someone spawned south of Pront) in 1~2 weeks after the server opened.
ElariaRO - Current server
And of course, my test server (Freya, eAthena, rAthena, Hercules)...I miss Freya, and I still have it.
All of the above servers are closed, except for TalonRO and ElariaRO.
I had lots of good times for each server, but there's many things I've done that I regret.
