Which combo is more valuable for site worth ?

a site that is strong in serp keywords and pr
or dmoz listed and pr ?

Traffic usually = money, so strong in serp keywords and pr.

I would view a DMOZ listing as a 'fringe benefit'.

Depends on what you're asking. If you're asking how site appraisals work that's different. If you're asking what to look for in purchasing domains, you left out age so I'd say I don't look at either of those stats. I'm a age / backlinks from something other than blog comments. I like to see top 5 backlinks with a AC 5 or higher. Domain age > 5 years. Diversity so more than 100 unique domains providing backlinks and > 1000 backlinks. Take the top 5 and check them for PR, if you see a bunch of donuts for PR then move on. AC rank isn't the best indicator of link authority. Study the anchor text also. You'll find a lot of domains where spammed to death before dropped. Low # of domains, high link counts and anchor text full of porn, pharma, trash. I've passed on a lot of domains that fit everything great except the anchor text from old backlinks was like a bad case of the herpes. I didn't want anything to do with the broad. =)

Getting back to DMOZ, if you find domains with DMOZ and they have age, you most likely aren't looking at spammed domains. Double check DMOZ and don't rely on tools. 95% are wrong about DMOZ listings. The domains WERE listed in DMOZ, but not currently listed in DMOZ is what you'll find most of the time.

HTH

As a general rule of thumb, a domain having better SERPs will have more traffic hence more revenue and it will be worth more.