I liked all 3 for various reasons, but I could never really get past the way the writers took no consideration as to technology and the passage of time in each series.
Atlantis abandoned for 10,000 years but under an ocean with a force field. Okay, maybe it is 2,000,000 years old (inconceivable that any organic species would exist that long AND still be the same when they were already pretty darn advanced from the beginning), but the Ancients likely kept it maintained and updated during that time.
Destiny made no sense at all. Tech is older than Milky Way stargates. Tech is clearly older than Atlantis. So, the ship had to have been launched before Atlantis. No evidence of self-repair tech on the ship, but it's largely functional and going along when the drive system alone should have burnt out from lack of maintenance. Even if the Ancients build things to last, stuff wears out. Nothing in the show really explains this away, and it's a lot to ask viewers (who understand basic physics) to swallow. The best you can accept is that the ship is much newer than it looks but built "old tech" because it is more durable (e.g., vacuum tubes are sturdier than microchips)...perhaps has self-repair tech that's stopped working because it's out of raw materials, etc.