Well none of these really have anything to do with competition, except 3v3 and 4v4. But I'll bite:
As far as single player goes, 8 player matches are just awful and I wish they could be turned off. I haven't had a chance to play with humans to see if 3v3 and 4v4 can be good in a controlled environment, but I can tell you I absolutely hate it in Classic Mode. I already don't like FFAs, and 2v2s were bad enough when your teammate is an idiot, this just makes it worse. I honestly feel that Classic is totally ruined by this.
Smash Tour, eh. It's okay. I feel like it'd be a lot better if I could pick my starting characters instead of them being random, and pick who in my team I want to use for each fight rather than just cycling through them in order. And it's weird how the final battle is a stock match but the winner is whoever got the most KOs rather than whoever survived, and the time limit needs to be longer since you too often don't get down to a single survivor. Feels like collecting a large team doesn't even matter that much. And while I understand that the simultaneous turns are necessary to keep the game moving fast, it's so frustrating how I can never reach where I want to go without getting intercepted by an opponent cutting me off mid-move.
I don't really like Master Orders since they're all too weird and gimmicky, but I really love Crazy Orders. Ironically the challenges are a lot less crazy, and I like the pressure of having to judge whether to cash out now or continue gambling for more. I just wish there wasn't a time limit so I could continue going for longer and longer streaks, just make it so that you don't heal as much between rounds as time goes on instead. And because I'm a total masochist, I'm disappointed at how there's barely any penalty for failure, could've sworn the Direct said you'd lose it all. Instead you still keep like 90% of your loot, kinda takes all the risk and pressure out of it.
Events have always been good, and these are the best they've ever been. I love that they've added extra challenge conditions to each one. Though I'm a little disappointed by the "hidden routes" only being based on unlocking characters, thought they'd be based on those challenge conditions. And again the 8 player ones are stupid, especially when they put you on tiny stages that should never have 8 players (Castle Seige? Really?).