Depends what I wanted to do... Some narrowed HP D60s would be a good choice...
Other things I'd consider:
-Volvo C303 portals
-Truehi9s in a spidertrax housing
The portal-teks are actually the best choice there for a lot of things... However, for hardcore rock-crawling the 60s or 9"s are the better choice.
Anyways, if a guy wants to run smaller tires with full-width axles, I think a HP D44 front and a 9" rear is a decent combination. I'm not big on full-widths. So, I'd probably go narrowed HP D44 and a Isuzu 12B rear, or maybe something less exotic like a waggy D44 rear.