Armada is not "pay to win". At least not yet.
Pay to win equates to buying that gives a player a distinct advantage, but few players purchase it. The only way that really figures into a miniatures game is through power creep, rare upgrades, or limited edition stuff.
Power creep isn't a problem in Armada, at least not yet. In some games, later waves make them selves worth buying by making them straight up more powerful. People that can continually invest large amounts of money in the new waves stay the most competitive through those expenditures. Wave 1, 2, and 3 ships in Armada still make up the backbone of many fleets. Every ship is still competitive. No one really gets an advantage over another player by purchasing 6 copies of the Chimera.
Sure, there are some more desirable upgrades hidden in expansions that may be less desirable to you, but there are lots of alternative and cheaper ways to get what you need. X-wing really dabbled in this with the huge ships, and it honestly wasn't good for the game, and they've remedied it to a large degree with the conversion kits in 2.0. I can't speak to whether or not the SSD is having the same effect here. I do honestly believe they should sell upgrade packs of cards however. Some upgrades exist only on one or two ships, and some of those are the most expensive ships. Yes, there are re-sellers that part stuff out, and prize support has helped supplement some of the gaps, but upgrade packs would still be popular, and help dispel the concept of pay to win.
FFG doesn't do limited editions or unique prize support, so this isn't a factor.