It has to be Rata Sum. It might seem odd not picking an explorable map, but this place wins for a few reasons. It was totes built by the Mursaat (headcanon, please ignore). It has a really cool futuristic look without going OTT. It’s the home of snarky Vulcan gnomes. They have a stage with breakdancing Asura and there is a Moa dance trainer. It’s the only capital city where the race’s bad guys (Inquest) are actually welcomed in. also Golems. I could go on, but snarky Vulcans pretty much covers it.
As I played Ele almost constantly in gw1, it will always have a special place in my heart. The visuals and attunement mechanics make me really love it. I have to say though, I do play my Warrior more, and I really love her too, so it’s a close one :D