Machamp all the way:
Speed
Machamp is the new Kingdra. With an attack that is an Auto KO, and for only one energy. Kingdra needed:
1 Horsea
1 Candy
1 Kingdra
1 Water
2 Spare Cards
1 Plus Power
Just to be able to grab the T1 Donk. Machamp doesn't require the two spare cards and the plus power. This is just enough to show that Machamp is capable of grabing the T1 Donk. Even more capable than Kingdra.
Power
Machamp has one of the best ways to increase his attack for a KO. Machamp Lv.X gives you that extra 60 damage and, if played at the correct time, can easily give you the win. Alone Machamp isn't a pushover either. For a single energy, Machamp can either get and Auto KO, or he can do 40. Since Machamp is supposed to be an early gamer, you don't need to worry about only doing 40 damage in the later game. Machamp also has one of the most underrated attacks in the game. Hurricane Punch is a great attack. Now most people fear flips, for whatever reason. Yet for only two energies you have a 50% chance of doing 60 damage, with the possibility of doing more. Coupled with the Lv.X Machamp's second attack is going to average 120 damage. Enough to KO almost anything in the metagame. (Raichu, T-Tar, Gengar, Dusknoir, ect.) Yet there is still more. Machamp's third attack, Rage is a great attack for finishing late game. 60+10 for each damage counter on Machamp adds up to massive damage quickly. Add in the extra 60 from the Lv.X, and with only 4 damage counters on you, you are able to KO every sensible card in the meta. Machamp Lv.X's attack isn't a great attack, I must admit. 80 for three isn't the best, even with the 50% chance of immortality. Overall Machamp is a great choice for power in this format.
Consistancy
This is where Machamp tends to have his issues. Most Machamp decks tend to have issues late game, if your opponent makes it to late game. Most people complain about Rage's energy cost, sadly they either don't know how to play Machamp or they don't believe in the Registark engine. Registark makes that 4 turn waiting process on Machamp's attack into a 2-3 turn ordeal. Nothing compared to four turns. Early game consistancy is where Machamp thrives. Being able to T1 with the right build is quite amazing, and overall not that hard. Using Chatot and Uxie you can T1 a Machamp almost 33% of the time. (I have done the math but I'm not gonna post it.) So overall, Machamp does have some consistancy issues but hopefully with the correct build you don't have to worry about late game.
Techs
Not too many techs go along with Machamp. The whole deck tends to revolve around Machamp and his speed. Two of the most important techs that go into the deck are, Weavile SW and Unown G.
Weavile: Is used to change Machamp's type to be able to 1HKO all Dusknoirs and Gengars.
Unown G: Is used to block out most of the troublesome cards in the format including Gengar's first attack and Dusknoir's first attack and second attack.
Matchups
Machamp has one of the best lists of matchups in the format.
Wins often against:
T-Tar
Raichu
AMU
Gigas
MagRan
Scizor Cherrim
Blissey
Often looses to
Salamence
Dusknoir
Gengar
If you look at that list there are very few decks that often win against Machamp. Gengar and Dusknoir can be taken out by some of your techs. Salamence is a rogue deck and doesn't tend to show up often.
There is my arguement for Machamp. Please enjoy.