Which Country is Best With MoS?

I just got it, and I can't decide which country is the best for MoS.

I find MoS to be more of a long range strategy, on smaller maps there tends to be better strategies that can cope with close combat. However saying this if you are to play it then choose a rich area that you can hold easy whilst attacking your opponents in as many places on the same turn.

On Eurasia maps you can play as Germany or Finland they are my prefered choices

So basically use Imp. Turkey in Europe and Europe+ and Germany or Finland in other maps?

Imo UK is the best, in world games and if it's 15k Japan is pretty great too.

Something about island nations that make MoS OP

Island nations are good picks while playing MoS indeed, specially because you have a long expansion range, making it easier for you to attack places like Germany from UK or China from Japan than the other way around.

It will also be harder to play with it in poorer areas, since you have two options:
Using infantries to expand, which will lead to a slower expansion compared to your enemies on early game, something that's essential;
Using marines (and submarines), which will lead to a good expansion, but will eventually make you run out of money very fast, limiting your expansion mid-game.

Of course this doesn't apply if you're playing 25k or 50k game.