Played the crap out of both of these series. Still P.O.'d that we're not getting Tales of Graces for the Wii, even if the updated PS3 version is coming to America(I'm sorry, but the Wii needs more RPG's).
My personal favorite Tales game is probably Tales of the Abyss. Just everything from the characters, to the story, to the music, to the gameplay just clicked for me. Though, I think art direction-wise, ToS was much more successful with their decision to use cel shading. It just fits the anime designs so much better.
The only issues I really have with this series is 1. Namco hates America, 2. The games are always sooooo long. Like, over 80 hours long for a 100% completion run. That's frigging insanity, especially since you need to go through each game at least twice to actually ACHIEVE 100% completion, and 3. What genius decided that every big sidequest in the game should only open up when you've reached the area right before the final boss? I mean, seriously. I'm just about to fight the final boss. I don't want to have to leave just so I can pick up the last few summons, or get everyone's ultimate weapons, or fight the super bosses. Why not unlock these things before I'm headed into the final dungeon, like every other game does? Why do you feel the need to break the tension that is the end of the game every time, Namco?!
As far as Fire Emblem goes, I'm happy to say that I've played and beaten almost all of them(the exceptions are Mystery of the Emblem, Sacred Stones and Gaiden). To be honest, I think the series took a hit when it moved onto the GBA. Everyone seems to love them, but for me those were the worst. They took a huge step backwards in terms of gameplay, the sprites looked way too silly for my taste, and the games just didn't feel right to me.
I loved Path of Radiance & Radiant Dawn, though, despite complaints about both games. I felt the series was finally moving forward...until the next two games were remakes of the first and third.
Sorry for the wall of text there.