For Pariden, outposts can be used for more than just territory grabbing. You can also use it as a way to get under territory for a big fight, so you get the +25% territory bonus. Expensive in mana early game, but it can help you win fights that you'd otherwise lose/be costly.
Also, I've won a game on hard as every race but Altar and Yithril this patch, and I'd say Tarth have the most powerful abilities currently, for the standard settings, at least. Every other race I fell behind in points, and had to fight a war vs the rest of the world, until I eventually ground them all down. Tarth I stayed ahead the entire game, because of all their abilities geared towards the early game gave me a massive amount of cities, outposts, and easy creeping with my sovereign. The only reason I went to war was that I was bored, and about to win by master quest, so I quickly crushed two races.
Most fun, however, is definitely Resoln. I like being able to control which shards I have, so I don't end up with 7 air shards of 12 total shards, when I have no air mages. Also, the most powerful tactical spell in the game, Dirge of Ceresa.