Space Armada is one of my favorite games for the intv, although the disc and side buttons made it frustrating at times. IMHO, it was impressively innovative for its time when compared to Space Invaders. The 2600 version had some minor tweaks to the formula, but Armada changed up the enemy weaponry with some cool stuff whereas the other console's Invaders clones didn't seem to (memory hazy on that though).
For me, Demon Attack didn't live up to its marketing. Imagic had some of the best, and surely the shiniest, boxes out there. As a kid, the box art was mindblowing and I begged my parents to buy it for me. But for me, DA was a minor disappointment. Phoenix the arcade game was fun, though.
It's interesting that Mattel didn't decide to clone Phoenix (1980) instead of or in addition to Space Invaders.