>>719692585
Don't bother with 1 or Gaiden unless you're interested in seeing how far the series has come
3 is a different enough experience from 12 that it could be worth it if you like 11
4 and 5 are fantastic games that you should try (though I guess if you still have other FE games to play, you can wait to see if the 4 remake meme will finally happen)
From the GBA games, 6 is the only one that's challenging, but that's partly because of bad game mechanics, still worth a try. 7 is a good beginner game, but rough for experienced players. 8 is Proto-Awakening and arguably the easiest game in the series.