alt Hacker NewsI use https://schtserv.com which supports both GC and Xbox versions of PSO.
The Dreamcast has it's own community servers and isn't compatible with Schtserv. Though I believe that might just be because Episode 2 wasn't release on the DC. I do have an account for the DC servers too but I wouldn't recommend them. The DC takes too much hassle to get online for the value when most people on the DC PSO server are there for the novelty rather than the grind.
Blue Burst (PC) has it's own community servers too. But I've never owned nor played PSO on the PC.
I've played a few hours of the gamecube version online. I honestly would rather play the dreamcast version, I'm not a big MMO person so the novelty is why I'm playing