I do think all FE characters are pretty cool in their own way. But in terms of who's my fave to play as... well, I find myself playing FE characters not a whole lot compared to past Smash games. I played Marth a lot in Brawl, but not so much now. Gameplay-wise I was never that crazy about Ike, and while I do think the additional of Robin is great in terms of uniqueness and mechanics, my interest in picking up Robin dropped. However, the same could be said about a lot of other characters this game. I'm not that enthusiastic to play a lot of them, especially the newcomers. It's strange because in Brawl I was the opposite. Gonna have to change my mindset or something. I'm only interested in Shulk atm, and might try Yoshi as a secondary. Hopefully I can get into Lucas just fine when he's released (can't wait!).
Anyway, despite all this I do love to play Roy in Melee and PM, and hopefully I would love him in this game (which I'm sure I will). Don't care if he's bottom of the tier list, I'd still main him. I think Roy's the only character I'm loyal to lol. Maaaybe Lucas as well, we'll have to see
My problem with almost all of this game's newcomers are that they are incredibly gimmicky, probably too unique. I want to say too unique, but that probably isn't true. Melee brought characters like Marth, Peach, Sheik, incredibly decloned Luigi, Bowser, and Mewtwo who were all very unique without being gimmicky and weird for the average player. Changes to Captain Falcon, Mario, Fox, Samus, and Link helped further set them apart as unique characters, breathing life into the game while they all remained very solid fundamental characters. Meanwhile, we had some gimmicky newcomers like Zelda, Game and Watch, and Ice Climbers, but they didn't feel excessive to learn. The many clone options for the already solid fundamental characters was a great way to appeal to many playstyles at the time.
Brawl brought Ike, Zero Suit Samus, Diddy Kong, Pit, Meta Knight, Ivysaur, Charizard, King Dedede, Wolf, Lucas, and Toon Link, who brought new stuff to the table, each with one or two gimmicks, but they still remained strong on a fundamental level and were easy to pick up for any smash player I knew. Falco's declone was powerful for it, too, as was Ganon's sexy command grab and some of his changes despite his fall. Olimar, Squirtle, R.O.B, Snake, Lucario, Sonic, and Wario (fat Jigglypuff) were fairly gimmicky, more noticably than Melee's gimmicky newcomers, but none of them felt excessive, and they were there for those kinds of players.
Now, it feels like Rosalina, Bowser Jr., Little Mac, Palutena, Robin, Duck Hunt, Villager, Wii Fit Trainer, Pac-Man, Mega Man, and all three Miis fall on too many extremes and gimmicks. Shulk and Greninja seem fundamentally solid all-around, almost like they're Brawl newcomers in the same category I placed Ike and Pit. Some characters were changed too much (*cough*
Marth *cough, you were just fine in Brawl) to feel comfortable for those who liked them in previous games.
I'd like to see more average joes, more Greninjas and Shulks, more Marios and Links, more classic Marths as DLC. As diverse as the cast is, I feel like the diversity is spread into too many extremes to appeal to everyone (the pure irony), and some characters took big blows to their fundamental design that weren't needed. Dark Pit, Lucina, and Dr. Mario were healthy for this game in my eyes, to sponge up the oversaturation of extremes, even if they are villains of the roster to many. To me, Brawl had it right for every character.
(keep in mind all of this is extremely subjective, and possibly nostalgia for games that have been out for years versus a game that's been out for less than a year)