I've played both games and they're quite different beasts. I think they've managed to get the differences right.
X-wing plays fast. You make the decisions mostly on the turn. it's a really relaxed game and our go-to at the moment.
I've played armada only a few time. You really need to plan ahead and I think the game requires more from the gamer.
I prefer x-wing. But that's personal taste and not because armada isn't a good game.
Both can get rather expensive but can be played with a smaller collection. I find it easier to ad a single fighter to my collection as the armada ships get more expensive fast.
Even so, x-wing drains most of my hobby money of late, but I'm not regretting it.
So what do you prefer? Quick thinking or longer planning?