I've gotten Megaropolis ~5 times on map 802.

It's definitely not the BEST map by far, but it's VT's area code, so I've kinda adopted it and learned how to work it.

777 really has an advantage for speedrunning almost all the other categories (based on the less than 20 total maps I've seen/used) Honestly, I haven't been able to Megaropolis 777 yet though. It's harder to manage it's land value and growth at full-map scale to improve population. Also keep having random-ish power bugs/outages a lot (on all maps granted, but really hurts when you don't have real estate for more plants).