ESD sensitivity of P-channel MOSFET vs N-channel
That's a loaded question-- so here is a loaded answer.

Does it matter?  Of course it doesn't.  You should be treating all semiconductors with proper ESD handling procedures, and making your designs have the proper ESD protection.  It doesn't matter if X is more sensitive than Y-- they are both sensitive, and both require proper handling procedures and proper designs.

Even a device that advertises as having ESD protection, or even something like discrete ESD protection diodes, should be handled as if it were sensitive to ESD.  

Remember:  ESD does different levels of damage.  A part can be damaged by ESD and not show any obvious signs, but then at a later date that damaged part could start failing and you won't know why.  

Now, is there a difference in ESD sensitivity between N and P Channel MOSFETs?  I have no idea.  I do know that there is a huge variation in sensitivity between different MOSFETs of the same channel type.  MOSFETs from 20+ years ago are much more sensitive than newer designs.  But even that is not a guarantee.  I would guess that the variation between MOSFETs of the same channel type is much greater than the variation between N and P channel types.   

The point being, I don't think that the difference between P and N channel types is significant, given that there is already a huge variation.  And since you should be treating all semiconductor devices with care, it really doesn't matter even more.