Found this thread saved in my archive of subscriptions and I thought I would contribute my findings.
I purchased a Powerbuilt 4,000 lb. Unijack, to replace the p.o.s. scissor jack that I know is pretty cumbersome to use. This is mainly for emergency flat tire situations, but it will also definitely work for at home tire swaps if need be. And the best part, it fits in the spare tire well after removing one of the bins. I'm yet to use it on the Jeep though, but hopefully won't NEED to anytime soon.
Powerbuilt 620470 Unijack - 4000 lb.
There is also a 6,000 lb. and 3 ton Unijack version, but I think those are both too tall to fit underneath the stock height WK2 before the lift and I know they will be too big to fit in the spare tire well with everything else.
Hopefully this will help someone searching for a better jack for their Jeep or Durango.