Performing Arts Peeps, Im on a Dilemma: ProCo Rat2 or Russian Big Muff?

[Holden® (Mr.ThumbzUP)]

I'm gonna buy a distortion for my "dirty" sound as support for my TS9-DX pedal.

Here are some notable users:
I. Big Muff:
David Gilmour (early phase)
Carlos Santana (early phase)
Smashing Pumpkins
Sonic Youth Mudhoney

II. Proco Rat:
David Gilmour,
Thom Yorke,
John Scofield,
Jerry Cantrell
James Hetfield
Krist Novoselic.

***Note: Of course I can't emulate their sounds as most of them have their units modified. But anyway, I still can tune into that sorta same atmosphere as their sound (kind of a common ground, so to speak).

To those who have experienced using both. Which would/did you choose?

*you can also add a pro's/con's discussion if it won't be a waste of your time.

Thanks in advance.