If you want to buy a bunch of lights there are qualities to appreciate about each variation, but the single most useful ZL light in my opinion is the H600w Mk II.
The best diffusion films have been identified by members here and by most accounts the results are virtually as good as the permanently frosted F models without the commitment.
To elaborate...
Floody (F) is really, really nice for use as a headlight, but the increased range of the regular is too useful to justify having a permanently clouded lense if it is your main light.
The regular version has a huge hot spot anyways that is only sometimes an issue to me at close range, while it is the additional range that makes the light so versatile.
The neutral (w) models eliminate much of the glare problem of "cool" white, while not losing much performance as compared to the higher CRI "c" & "d" variations, by the numbers.
While I've not seen an H600Fw or H600Fc, I have an H51Fc (floody, high cri) from 2012 as reference.
To me the H600w is too useful to keep in the headband, I permanently secured a clip to the light and it lives in my pocket as an all purpose 24/7 carry light.
It gets the most use by far compared to any light that I've had before, day and night, it gets used on full power and firefly and all in between, seems like every month or so I swap out the battery when is about half depleted.
It's great as a compact pocket light, and the utilitarian non"tactical" appearance is much appreciated. For being so light in construction it has held up beautifully to being dropped and bashed around since it got the clip last summer and became my main light. I've dropped it squarely on its head onto concrete multiple times (the mass of the 18650 being stopped by the circuit board) -which I'm not proud of but the light is no worse off for it.
The threads that have best helped me to decide have excellent comparison images shared by forum members, there are some great old ones back there, the current one floating around nearby is:
http://www.candlepowerforums.com/vb...s-H600F-(Floody)-vs-H602-(no-reflector)-beams