I don't really play much anymore but as a long-term players whose been through quite a few map wipes I actually find that the first few weeks after a map wipe are always the most fun. Building a community is what I enjoy, everyone exploring around, finding cool areas and showing them off.
For me, I think the main reason I stopped playing was that the game was getting too technical for me. It seemed like everything had been done already and there wasn't much point in playing.
My vote shouldn't really count for anything but I always find a server restart re-invigorates the server and brings in new players. What I didn't like about the last one was that buildings and items were kept from the previous map. I think if a restart is done everything should be started from fresh, 20 of us spawning in to a completely new map and exploring is always the best fun.
I don't think anything will ever beat the first time mobs were brought into the server, running around desperately trying to build tiny forts to keep them out, seeing people get swamped by creepers in the distance while trying to reach safety. That's what minecraft is about. I think that keeping the same map for too long just leads it to becoming stale.
Maybe the best of both worlds (pun intended) would be to have a second server with a new map where people like me can go and start from scratch. That way people who have put so much time into the current server won't feel like they're losing anything. I remember the first map reset everyone was raging over it but it all calmed down in a day or two when they realised that they had a completely new landscape to sculpt.