It is a very simple thing. The performance of HEAT warheads depends on the caliber of the shaped charge, the explosive filler and the liner material. If we assume that both Russia and Germany use a similar level of technology, then the PzF 3 will end being better, because it can (and does) use larger warheads.
By this PoV the RPG-7 is even "better" than the RPG-29 - not because it offers superior performance at the moment, but because it was capable of staying a potent threat even nowadays. The warhead of the RPG-7 ammunition is not inside of the launching tube, so performance could be increased; the diameterof the warhead increased from 73 mm in the 60s to a 105 mm tandem warhead in the PG-7VR projectile, which offers penetration performance similar to the RPG-29. The main problem with the RPG-7 (except it's old age and outdated materials) is that the launching tube is limited diameter, which means that larger warheads will be slower and therefore have low velocity and range. The RPG-29 has twice the velocity and range than the PG-7VR projectile.
The PzF 3 is designed in such a way, that the launching tube is part of the ammunition. So both launching tube diameter and projectile diameter can be changed, while the original launcher can be retained. The manufacturer has developed several versions ranging from 60 mm and 90 mm (e.g. used by Switzerland) to the basic German version with a 110 mm warhead, if required an even larger version could be designed in the future, using the same launch unit - not possible with the RPG-29. The claimed penetration for the latest version (PzF 3-IT-600) is about 1,000 mm RHA (which is still too less to beat a PT-91 with ERAWA-2 ERA). Another significant advantage of the PzF 3 is that its launcher is incorporating a laser rangefinder and a ballistic computer. The main drawback is pretty clearly that less ammo can be carried by a single soldier.
Here are two packed PzF 3 launch unit:
And here is a loaded launcher and ammo: