Karate Chop/Cross Chop Machamp

Karate Chop isn't that far off from Counter in terms of DPS. It's slightly lower, but also allows for much easier dodging. As far as charge moves go, Dynamic Punch is by far the best if the bunch. Cross Chop is quick and hard for opponents to dodge (so maybe good in PvP down the line?) but Dynamic Punch outputs much better DPS. Close Combat is pretty mediocre, as it's fairly low damage for a one-bar move.

That said, I wouldn't TM your Machamp. If you find yourself needing another one with C/DP, you can always go after one from a raid and TM it as needed. The same can't be said for this one with legacy moves.

I took the leap & TM'd mine a while back & was lucky enough to get KC/D Punch. He's seen alot of use, great for dodging in gym work & KC generates energy quickly for DP. Also in my raid team & does great there also. Cross Chop pales in comparison but my only reservation about you doing the same is PvP as already mentioned, no expert on that score tho. C Combat not great.

It's awesome.
Karate Chop is amazing for dodging (Counter is bad at it).
I kinda use only my KK/Dynamic Punch (TM'd) Machamp for fighting Gyms (Blissey, Snorlax, Chansey).

As applies to Machamp:

C/DP is best set, 100% of potential DPS
KC/DP is 97.5% of potential DPS
C/Close Combat is 88.4% of potential DPS
C/Cross Chop is 88.3% of potential DPS
KC/Cross Chop is 82.9% of potential DPS
KC/Close Combat is 82.8% of potential DPS

Any of Hariyama's movesets are about 93% as effective (with higher TDO) as Machamp's equivalent; a KC/DP Machamp would still outdo any Hariyama in DPS, whereas a C/DP Hariyama would outdo any other moveset. A C/Close Combat Hariyama would be outdone by any of Machamp's sets above.