Definitely Melee. Been playing Sm4sh for a month now and while it clearly needs to develop, putting it at EVO so early won't really help that much, I don't think. Give it time to develop a natural meta before putting it on the tournament circuit, give it time for the potential balance patch, then when we're out a ways bring it to more big scale tourneys.
As it is right now lots of broken things are in the game -- not even matchup/character wise, but weird glitches and such. A series of patches in inevitable and I think they will be important to how the meta forms.
I don't hate Sm4sh at all, but I do think Melee is more interesting competitively due to how aggressive it is in comparison. I have ~600 matches logged into Sm4sh (in no way enough to make a really hardcore critical analysis) and my overall playstyle right now is centered around trapping people who abuse defensive tactics, which in general are very, very safe. Things like air dodging and back dodging are very harshly abused both by CPUs and by online players -- many of which I assume are Japanese children going by their tags/playstyles -- and while I usually win unless they hit a streak of luck, it is enough to realize that some of these defensive options could, in the wrong (read:salty) hands be really abused. This leads to a very slow, methodical (and interesting to play, though kind of repetitive and boring to watch) playstyle. It says a lot that the CPU constantly uses air dodge their entire way down during recovery, specifically when the game is centered so much around air game. While these tactics are easy to work around, they do create a mindset that punishes aggression. Oftentimes I've found the best way to approach is to air dodge towards my opponent, or to wait for them to attack, spot dodge, and then attack immediately. Surely a meta will evolve around this and it will get more complicated, but if we're putting it at Evo strictly because it will gain a large amount of participants it wouldn't be surprising if a large amount of people played like this.
This isn't a qualitative statement about the game itself. As I said, I don't know enough yet to make a full statement and I've been playing the game for a month. I like it enough, but I think Melee is, at least currently, better suited for a competitive competition like Evo. Melee was hype as hell in '13 and '14, and I don't see any reason why that should stop just because Sm4sh came out. It's shiny, it's new, and it's pretty cool, but it needs time on its own to breath before we replace Melee with it at Evo, specifically if balance patches and significant changes could be made to it that will effect the meta in ways that could greatly influence how the game is played.
It deserves a spot at Evo for sure, I'm just not sure if it's now, or if giving up Melee is worth giving Sm4sh the spotlight. I like it a fair amount even with its flaws. I'm sure the community will have to decide eventually.
Edit:
I think this thread is counterproductive, especially this early in the game - there isn't even an established tournament scene for Smash 4 yet, the Wii U version (which presumably will be the game to appear on the EVO stage) isn't even out yet, and so people are making uninformed votes at best and spewing inflammatory garbage at worst.
Rather, I'd like to focus on how to bring the scenes together at this point and try to push for having both games at EVO. From experience, the set of people who compete in Melee are relatively disjoint from the set of people who are interested in competing in Smash 4, and thus I feel like having both games at EVO could bring in a HUGE number of entrants. Let's not forget that Melee has shattered one stream record already and ran nearly 1k unique entrants last year. Smash 4 is going to be enormous as well, since there'll be a huge influx of new casual players.
All we can hope to do in arguing Melee vs. Smash 4 this early in the game is making uneducated insults, which is what this thread seems to have devolved into pretty quickly. Without getting into the specifics, nearly all the comments in here attempting to downplay either Melee or Smash 4 have been oversimplified.
What Toph says here is great. People are taking things as a chance to hate on players for games that haven't even developed yet. While I think Melee deserves to get the tourney if they
have to chose a single game, I think what he says about pushing for both is a great middle ground. He's also right about people making uneducated, myopic insults about the nature of both games and how they work competitively and what makes them great (hint: its the people who play them).
Only a few of us have had the privilege to play the game yet. We are all playing on inferior hardware, at least until the New 3DS comes out. There is literally
no way we can know the nature of the game as it will be given some time. For all I know, everything I mentioned above could be patched out in two weeks and the game will be amazing competitively.
We need to give things time to breath. So even as someone who comes from Melee, and even as someone who prefers Melee to Sm4sh, I think the best assessment is to wait a bit and give Sm4sh some time to develop.