Trying to get into MUDs - any suggestions?

Hey folks,

just in the last few days I've really become very interested (probably one of those ADHD micro-obsessions) with trying to play a MUD or MUSH. I'm a long-time tabletop RPG GM, and I've been diving into retro games lately. It feels like it should be right up my alley!

That said, I haven't had a great experience with my first little foray. I've had some software issues accessing some of them, and others are simply dead. It sounds like Gemstone IV is super popular, but I don't want to jump into a neutered experience (and I certainly don't want to pay to play from the outset!).

I'm hoping to try a few more, but it would be great if anyone has: (a) specific ones that they think are still great, so that I can feel more sure that it's worth the trouble of getting set up on and used to a specific MUD. (b) advice about getting started!

Thanks for any input! =)