I have never cared for the Heng Long/Taigen front fenders and as WOZ C/O Shapeways makes/sells replacement Front and Rear hinged fenders in both the early and late patterns that's what I use,
Dolls house sites sell the exactly correct hinges and
www.prime-miniatures.co.uk sell the M3 Nuts,Bolts and Washers as well as nutspinners should you need them.
The front fenders are a doddle to change but the rears are more challenging needing the PZ4s rear panel removing. (One Piece Glued on)
If you are going for a Aus F2/Aus G or Aus H the front Glacis in front of the driver/ radio operator was reinforced and WOZ makes/sells a very nice part that with very little extra work looks good (M4 Bolts instead of the faux moulded on ones)
The Aus F2/G and the early H only had the Schurtzen armour around the Turret and the Aus H and J moved the radio aerial to the rear left flank which makes the accurately detailed radio aerial deflector on the main gun obsolete and the fixed cupola makes converting the twin hatch pre-Aus H cupola into a single hatch Aus H and J much harder.
Unmodified Heng Long and Taigen Panzer 4s have a bit of a Jelly Mould appearance to my thinking but very little work lifts them into being very nice facsimiles and as they served in every area that the German Army fought during WW2 the sky is the limit on camo patterns.