Depends what you have really...
MT deathball should work up until 3-5% ranking in POC, but after that it is very likely that you will need to use HT + TD/Arty deathball to progress further.
I am personally running a hybrid of both since having too much arty = very hard to auto climb poc. I know some of the top 10 is running stuff like 2-3 HT, Lots of Arty/TD, and anything else you have that can boost your Damage Reduction rating (T-70 and PT-76) and probably cheap emergency tank (e.g. Satan)