I would have to say Risk Devolution.
Devo has no shelf life, each game is just too dynamic
I don't really understand this...
I would say Devo has the best replayability factor because of the fact that the game is so dynamic.
I would be interested if you could explain this more.
In addition, Devo has no ridiculous choke points (well, only a few), and all but a very select few are tree-based.
I prefer this because it allows the game to differentiate between the pros and the mediocre players.
Anybody can see the choke points in NG clear as anything, they are just so conspicuous. There is some of this is Devo, but there are some points that are ever so subtle which allows for advanced players to gain the advantage, where a worse one would not be able to.
This is mostly because of that fact that Devo has a large expanse of land with few defining features other than trees and base placement.
Another thing is the continent bonus.
SS have a change to become a lot more powerful in NG because a port taken is not a county blocked, it is a continent. About 10 income on top of the income of that territory. Likewise, there are much fewer places that are safe from SS in NG than in Devo.
I have one many a game (and I am sure everyone has) where I destroy the opponent on land even though they have a huge fleet marauding around. In NG they could just post those ships on a continent-crossing and that be the end of it.
To some up, I would say that Devo is better just because it has more ways to differentiate between Pros and others, as well as being an overall more dynamic and player-determined game. (Much fewer physical factors to confine players)
NG is more friendly to beginners in that if they can grab a continent they can probably hold onto it for hell, which is good for them, but only if they can survive the mosh that is the first 5 rounds in NG before people are established, and others killed.