baller...

I wouldn't worry too much about upgrades from stock at this point. just getting on a fatty will be fun enough as is. and don't get sucked in to the "blingy" rear derailleur. the RD is a money suck - the difference between an SLX to an XTR, for instance, in price doesn't justify the slight upgrade in performance - IMNSHO, 'specially for fat bikin'....

as you grow to undoubtedly love your newfound fatness, the upgrades that will make the biggest difference - feel, performance, durability - will be in the wheels: lighter/stronger/holier rims, lighter/wider/bigger tires, tubes/no tubes, etc....

from there, you can work on customizing and fitting the bike to your riding style and purpose.

for instance, some FORC'ers have changed their drivetrains from 2x9 to 1x10 setups. others have swapped out the stock saddle for a Brooks saddle. other swaps/upgrades you'll see (that are highly dependent on personal preference) are handlebars, stems, racks, etc....

I think the Pugs Ops is a great option for you, as would be the Mukluk with its symmetrical rear spacing and countless braze ons. sounds like pricepoint will be the ultimate deciding factor for you, and there's absolutely nothing wrong with that!

my fat bike purchase wasn't planned, calculated, or researched one little bit. I walked into the LBS on a whim, saw it sitting in the corner, said "oooooooo, shiny....." took it for a quick test ride and....

boom.

I went fat.

prolly the best bike purchase I've ever made from a fun/price ratio.... and I have ZERO regrets with that purchase.