I am dedicating my effort towards one character getting in and that character is Mega Man.
Mega Man is one of three characters I support that I expect to show up (since I do believe third-parties will return with one new addition); the other two being Mewtwo and King K. Rool. Mewtwo might as well be good as confirmed and King K. Rool is the most likely newcomer (in my book), so I'm not particularly concerned about them.
I choose Mega Man because unlike these two, there is a scent of uncertainly revolving around the character. He could very well get in due to his massive popularity and importance to video game/Nintendo, but he could also miss out if Capcom and Sakurai fails to communicate with each other on the subject. Considering that this will be my last Smash, I want to be able to make whatever effort we can count and hopefully bring the character to Smash.
There are, of course, other characters I would love to see that I feel also have realistic odds; including Isaac, Dixie, Toad/Bowser Jr., Samurai Goroh, Roy and Mach Rider; however, those are not characters I would have an issue with Sakurai not including as I consider them extras. The rest on my wishlist are either characters that are unlikely (Paper Mario) or have no chance (any non-Mega Man third-party on my wishlist (not counting Geno)).
So basically, other characters on my wishlist are either characters that I feel as near guaranteed, realistic characters that I consider as bonus, or unlikely characters that I have little to no hope for. Mega Man is a character I feel has a solid chance of getting in, but also a real chance of missing out. This circumstance would only make me even more excited for the thoughts of Mega Man's inclusion in Smash. If Mega Man were to be confirmed at E3, I would be incredibly ecstatic. Not only would Mega Man finally be in, but Mewtwo and King K. Rool will almost certainly be in as well, so it would be a matter of waiting for the game.
So what am I waiting for? Might as well hope that whatever last push is done gets Mega Man in Smash 4 and pump out a kick*** thread should we be granted a new one.