From playing through most of the series again recently I have to say I've had a hard time going back to the GBA games after playing FE 4 and 5. I can easily move back to Path of Radiance and Radiant Dawn, it just seems the GBA games are lacking and have nothing major outside of the Weapon Triangle. I will say Fire Emblem: Blazing Sword was probably more balanced than Thracia or Genealogy. But Blazing Sword however removed the skill system which added more depth and strategy aspects to the game. I guess overall I find Genealogy to be the best simply for the lovers system and the scope of the game. I mean you literally moved across the Continent to liberate kingdoms. I was also a big fan of the skill system even though some skills were pretty broken especially if you had the right set of skills on a character. The downsides I saw in Genealogy was that magic was not balanced since Wind just seemed to outclass everything except for maybe Resire. I mean the base Fire book had such a high amount of weight it really hindered the user. Balncing issues aside FE4 probably had the most engaging story of the whole series that spanned almost 2 decades as opposed to the general 1-2 year campaign.
What I liked about FE7 was I generally did enjoy the story, but have found myself having trouble going back to it now after recently playing the SNES games. I just feel the GBA games removed some features I enjoyed. I just found it to be more basic and it further broke the weapon triangle by giving a larger bonus for a triangle advantage. I did like that they balanced the magic system more by making tomes have reasonable weights. So when I first played it I loved the GBA games and probably out of them FE7 is my favorite. I do see them as a good starting point to be introduced to the series.
So in no way do I dislike the GBA games, just prefer some of the features in the SNES games that returned for the GCN and Wii iterations. Heck Thracia has one of my favorite features in capturing enemies, but I'm not sure if I'd want to see it again for the fact that Thracia was created around the aspect of capturing for weapons and money. I'd love to see another Fire Emblem like Genealogy of the Holy War though just because I enjoyed the big maps.