I actually just bought White Knight Chronicles off of another CAG member, and I say it is somewhat similar to PSO (definitely some differences), but it's not too pricey, I'd say check it out. From what I've seen there is definitely still an active community, can't tell if it's "thriving" or not, but I highly recommend you check out what it has to offer. Feel free to PM me with any other questions you have about the game (this is currently the main game that I'm playing)