I prefer (and so do almost a majority of Minecraft players) pvp servers that promote griefing (or put into kinda words, Raiding) if it were survival, it adds that extra challenge, to fight, defend your base, to kill/raid/loot, but as long as there is pvp you'll see me on it, lol.
Towny is a similar plugin to Factions, it's the same but it has a nice system whereas you have mayors, assistant, and would work well if you think the Factions plugin would promote griefing. The only problem through is that you'd find that many players have used Factions more, and would find Towny confusing.