Warning: Wall of text.
If you look at my signature, you'll see Bandana Dee has a lot of competition to go up against.
Melee took me few hundred hours to decide between Marth, Link, and Fox. Then after I booted Fox out, it took me over a couple thousand hours to choose between Link (powerful hits + projectiles) and Marth, with Marth ending up being my Main in Melee because his gameplay feels perfect in Melee along with his safe longrange, quick, and powerful melee attacks. Sadly in Brawl I don't like his (and Samus's) gameplay, and I don't know why.
Brawl I'm still deciding because it added a lot of characters that were my favorites for Nintendo characters. Meta Knight, Lucario, Charizard, and Wolf. WIth R.O.B. being there for being a shining example of Nostalgia over things that are useless (and I like his awkward moveset). I never had a chance to play Kid Icarus before so I couldn't enjoy the original, but Brawl made me love Pit, spammable arrows, quick melee attacks, and can flap around a bit, so he's become a contender for one of my mains. Link remained one of my favorites, and is my favorite character to watch in Brawl.
I haven't had much time to decide between characters on Brawl so far.
In SSB4 they are making quite a few changes. Some of the slower characters seem sped up, so King Dedede and Ike have a shot at being mains, because they are just so darn fun to use, but they are way too slow. Speaking of which Sonic is getting changed around, so maybe he'll get some better KO options, so I don't have to feel like such a jerk when putting people to high %s (even if it suits Sonic.....). I've never tried the newcomers, so I could like any of them, but Mii Fighters look the most fun to play currently.
As for Bandana Dee himself, I like long weapons. One of my favorite Melee weapons is a Scythe (others being swords, and claws). Though they are rather rare unless you're going into anime-ish type games. Spear is somewhat similar, just less slashy (usually), and more pokey. I loved marth for his safe long-range, quick attacks. I feel Bandana Dee will be a lighter, stab oriented, multi-jump version of Marth, but with projectiles (saying that VERY vaguely of course). I feel Bandana Dee would be right up my alley in terms of gameplay. While Bandana isn't my favorite character (Meta Knight holds that honor), he has a good chance at being a main.
Never really thought too much about his gameplay before, I was basically supporting him because he deserves to be in.
Edit: Slight edit. Apparently I had another part of a post I was going to make from earlier in there. I just cut it out. Sorry about the confusion for the out of context stuff.