The Daily Grind: What’s an older, underrated, or obscure MMO you’d recommend to us?

We all know what the big MMOs out there are, but those tend to push some other worthy titles out of general awareness. I say, let’s push back on that today and spend our time in this space highlighting some MMOs that might not be in the Top Five but are still pretty cool in their own way.
So what’s an older, or underrated, or (semi-) obscure MMO that you’d recommend to the Massively OP community? What title needs a little more attention and love?
I’ll kick this discussion off with a recommendation of my own! I’ve been easing back into RIFT these days and finding it just as fun and addictive as it was in 2011. This MMO’s totally fallen off the radar, but it’s still very playable with a small but passionate community. I’d love to see it mount a comeback of any kind.
Every morning, the Massively Overpowered writers team up with mascot Mo to ask MMORPG players pointed questions about the massively multiplayer online roleplaying genre. Grab a mug of your preferred beverage and take a stab at answering the question posed in today’s Daily Grind!