Between the Randy Andy show, er, the Andy and Randy show, I would have to give a little edge to the guy whose last name starts with a P!
Seriously, both of these gentleman operated at a very high level of competition and I like both of them since they are each in their 60s. I knew Randy early in his career when he was Autocrossing ( clear back when the Nationals were in Salina, Kansas ). Not claiming much, since even though I was helping with the Logistics of the Nationals and even did some Emceed some event parties , he has no clue who I am ( evidenced at the Solo Nationals when my son and I chatted with him in the food line ). I always followed his success because it was cool seeing an Autocrosser jump up to the Big Leagues and do so well. Andy was someone to watch because he was a GM Contract Driver for so many years , ran at LeMans and did a little Nascar, but to say which one is better is a tough judgement. Ironically they both ran together with the K-Pax Team ( World Challenge ) , so as Teammates one would guess they were pretty darn equal.
One thing, over the years, they both seem to really like GM products, so the glowing reports each have had for the GT 350 and GT 350R , have been a true representation of what an outstanding machine these beasts are. Expect them both to be glowing over the GT 500, also.
Best part is they both exemplify that age is relative , since in their 60s each is still blazingly quick on the track. Heck, Randy Pobst jumped in cars he had never been in before and went out and won the Solo Nationals after not competing for decades.
If you go by Championships, alone, Randy would edge out a bit, and if you add in their time as Teammates , Randy won the Championship when they were both racing the Volvos at K-Pax.