I hope mega pokemon will be revealed soon as well, I mean I do not mind the wait since we have been getting all this great information on the new pokemon in S/M. this is going to be a bit long but I would want to pick a pokemon from each type to receive a mega evolution. I noticed back in X/Y they had done this so every time had some sort of representation. My choices will obviously stay away from the starters, while at the end of this I will just say my top three legendary pokemon/groups to possibly receive one. So here my list:
Normal- Ursaing (Normal), Bug-Yanmega(Bug/Dragon), Dark-Zoroark (Dark), Dragon-Flygon (Dragon/Ground), Electric-Luxray (Electric/Dark), Fairy- Togekiss (Fairy/Flying), Fighting- Hawlucha(Fighting/Flying), Fire-Darmanitan(Fire/Psychic), Flying- Noctowl(Flying/Psychic), Ghost- Cofagrigus, side note for this one is the mega would be based on Cofagrigus not living in the coffin, thus adding the fighting type(Ghost/Fighting), Grass-Gogoat(Grass/Rock), Ground-Excadrill(Ground/Steel), Ice-Cryogonal (Ice), Poison-Weezing (Poison/Fire), Psychic-Girafarig(Psychic/Dark), Rock-Gigalith(Rock/Steel), Water-Lapras(Water/Ice)
Legendary Top 3:
Keldeo(Water/Fighting), Ho-oh(Fire/Flying) and Lugia (Psychic/Flying), and the Regi trios which I can see each one gaining the type of another Regi as followed, Regice(Ice/Steel), Registeel(Steel/Rock), Regirock (Rock/Ice).
I would go into more details about each one, such as stats and abilities, but I will save that for another time, these are just the pokemon I hope receive a mega evolution this generation.