I would've loved to see Machamp get a Mega. It seemed like an obvious Pokemon to give one to. Despite that I've still had lots of success with Machamp, but when Pokebank comes out there will be little reason to use him over Conkeldurr. Machamp may also see competition with Mega Medicham now. Mega Medicham is much faster, with 80->100 Spe, and a greater threat offensively thanks to Pure Power, but has 30 less base HP and none of the utility Machamp offers with his DP confusion.
Here are the two sets I've been using:
All out Machamp @ Expert Belt
No Guard / Adamant
212 HP / 252 Atk / 44 Spe
Stone Edge
Ice Punch
Dynamic Punch
Payback
The Expert Belt boost is great with the amount of Pokemon he hits for SE with this four move coverage. Only Electric, Fairy, Poison and Water, and a few dual-types avoid being hit for SE damage.
Trick Room Machamp @ Expert Belt / Life Orb
No Guard / Brave
252 HP / 252 Atk / 6 SpD / 0 IV Spe
Stone Edge
Ice Punch
Dynamic Punch
Eathquake
Machamp is a force to be reckoned with when Trick Room is up. This set gives just as good coverage as the one above. You could swap Stone Edge for Thunder Punch for even more SE coverage, but a perfect accuracy Stone Edge is just too good to pass up. It's also tons of fun in rotation battles on wifi