@mbun As far as accessibilty, I would go so far as to say it's the easiest to pick and up and play.
But I'm weird when it comes to being given character choice, regardless of the game. Take Mass Effect 2 as an example. I love that game, but my biggest gripe with it is, to me, it gives me all these different characters when I don't need/use them. And with how the story is designed, you practically need to use Legion for the rest of the game once you meet him, and that's only his loyalty mission and the Suicide Mission. So characters like Samara, Jacob, Zaeed, Miranda, Kasumi, Jack, and even a couple of my favorites in Thane and Mordin I never really use, because there's too much choice.
I'm someone who wants to give every character/party member/etc. their fair shake and time, so to me, having a cap of like 6-9 characters max is my sweet spot, and nine is pushing it. It's why when I look at ANY fighting game roster, I think to myself, "Pick one, ignore the others" and that makes me feel weird.
But back to Smash: I DID own Melee when I still had a Gamecube over a decade ago, and fighting against the computer by myself just wasn't fun. I've given other fighting franchises a shot, but I've just come to accept it isn't for me. I will say though I enjoyed Ultimate's E3 presentation more than anything else from the show, and I'm a Kingdom Hearts fan.