I voted against the Hill because I don't really like the idea of upgrading the Hive units there. But I'm always happy to upgrade my main army, especially if I've already upgraded them in the city. It doesn't appear very often, maybe once every 10-20 games, and sometimes it appears in places where there's no need to upgrade anything. And if everything is already upgraded in the city, then there's no point in upgrading anything there... it just wastes extra moves to save 1500 gold per week. The benefit isn't great; an extra conscript is better than a Ford. But if you're upgrading Hive units, that's a different story, and it's a good bonus.

Added 4 minutes later
Although, the Hill is conveniently located, and the Swamps and the secondary unit are even rarer. So, in principle, I'm in favor of the Hill. I just indicated that I was against it in the vote.