Surprised at how many people didn't click with DQXI. It's basically a modern-style Chrono Trigger (yes, I just said that): turn-based awesomeness, super charming writing peppered with moments of real heartbreak, a Yuji Horii penned story and Akira Toriyama art, and a bunch of modern amenities such as a variety of ways to make the game way more challenging and a full built-in "demake" mode.
And they're all more or less like that, which is why I voted DQ. The series doesn't have a single bad game, and even its worst entries still have reliably strong aspects in the story, music, and art categories due to the consistent staff. DQ1 basically invented the JRPG, including plenty of gameplay elements still used today. DQ3 has aged beautifully and is still great fun to play to the point where they're making an HD remake of an NES game on modern systems. DQ5 told a beautifully tragic story that focused on a family and the passage of time. DQ8 showed the super-linear FFX that you could still have an RPG with actual exploration (and fully orchestrated music) in it. DQ11 is basically the only place to still experience a classic turn-based battle system with AAA modern polish (sorry Pokemon, you gotta step up). And on that note, the monster design is super-appealing, often hilarious, and far outclasses Final Fantasy's.
That being said, FF6 (3 on the SNES) is still the best RPG ever, so I gotta give Final Fantasy credit for that masterpiece. 4, 7 and 9 are also really solid. But I honestly lost interest in this series around the turn of the millennium, and DQ is still going strong.