Illyros is my current Gor fave. Have had a couple of good scenes, met some great people. Excellent build, pretty avatars, good roleplayers. And probably the only sim currently in SL Gor that is actually a roleplay sim and not that quasi-lifestyler mix.http://counterearth.enjin.com/
I've got a friend playing in Hotchburg, so pop in there from time to time as well. Decent build, few avatars from the past (flexi and orange skin, no mesh, etc.) but couple of pretty ones as well. Haven't seen much in the way of roleplay there, just been stalking my friend.
Outside of Gor, Remnants of Gor is still going strong if you like cyberpunk, sci fi, with a sprinkle of post apoc (Melna's having a major sim build overhaul done, at which point I think they're shifting the setting to a new colony setting.) They also have an interesting meter/HUD system in which you loot "nodes" for items, and can buy/sell the items to other players, also have a currency system built into the HUD, and NPC vendors on sim. Combat is also related to the HUD, but more with dice rolls augmented with what weapons your using, what armor you're wearing, what cybernetic implants you have, etc. Usually busy, occasionally chaotic, interesting mix of avatars (heavy on the furries/dickgirls/anime/kemono av's but some human and some really interesting "alien" av's as well). Most of the av's are very well done, if primmy. Excellent build.http://www.remnantsofearth.com/
Crest of V'rekmar is a fantasy sim. Played there a while back, was fun then sorta died off as the "royals" roleplay took over and they changed the sim build to focus more on the royals, sorta leaving most of the other factions out in the cold. Have poked my head back in to see how things are now, admin was friendly and helpful at least, which is always a good sign. Wide variety of interesting avatars- from human, to elf, to orc, to dragons. Most of the av's were well done. Good traffic, av's inside and out in public areas. Decent build.http://vrekmar.enjin.com/
Whiskey City is an urban/crime roleplay sim. Bit unsure about the theme, think it's sorta like "Crack Den" with nekos and elves. DCS meter (75L to purchase required meter, then 1k+ for a DSC weapon). Build was typical "city". Avatars were decent, mostly human, one neko, one elf noticed. A few avatars were from the past. Traffic was decent, but virtually everyone was holed up inside and coupled up so no clue about the quality of RP, if any.
My timing was SLT 7pm-9pm or so, when I was popping into these sims, to gauge traffic, my usually arpee time.