Agreed with eveything but the last line; personally, I like the Kart games better.  They're just more my type of game and I can still have a blast playing alone, whereas Smash gets kinda boring by yourself.  However, regarding local multiplayer, I think Smash is much better simply because I hate splitting the screen in Mario Kart.

I do agree that Melee beats the pants off of Double Dash but I'd actually put both of the Wii entries dead even.  Both are excellent.

Regarding this gen, MK8 is gonna be hard to top for me, especially since I like the Kart series more.  The amount of fan-service in Smash is undeniable though, but then again, the bad-ass DLC coming to MK8 gives it more points as well.  

Basically, if you have a WiiU you can't go wrong since you'll have access to both of these gems.  Yes, Rainy... that's a hint.  

From the demo, and because I loved MK7 but not as much MK8

Mario Kart 7 > SSB3DS

SSBU > Mario Kart 8

Mario Kart as a casual game, Super Smash Bros. as a competitive game. Although both of them excel in each category and have their deviations. For example: MKDS - excellent competitive game, poor casual game, Brawl - vice versa.

And Super smash Bros. Melee and Mario Kart 8 and easily two of the best games ever made.

Smash Bros. Brawl is one of my favourite games, and I've enjoyed it and Melee way more than any Mario Kart. The only one that comes close is MK Wii.

SSB over MK... this need a poll.

Did you not hear the news? I decided to be a multi-console owner for the first time this Gen. 

I'm planning on re-buying a Wii U within the next 6 months

Boom!

Ha! This is true

Mario Kart 64 over Super Smash 64

Super Smash Melee over Mario Kart Double Dash

Mario Kart Wii over Super Smash Brawl

As for Mario Kart 8 vs Super Smash 4, it's anyone's call.