I'd say for most lines. Whatever the premium model was. Will be the most collectible and expensive for collectors. Because it was the best. Also it was the most expensive. So, it is the rarest.
I don’t have access to sales figures at the ready. I’m not sure how many folks do, to be honest.
What I do know is between the two models during the final run of PowerBook G4s, Apple stopped accepting new build-to-order/configure-to-order options for the 15-inch model, the A1138, on 10 January 2006 — when the A1150 went on sale (and exhausted stock on remaining, non-BTO/CTO A1138 models by 22 February 2006).
The A1139, meanwhile, stayed on sale through 24 April 2006. Both went on sale 19 October 2005. The difference in price for the display and form factor was USD$500. Aside from display, mass/dimensions, and one difference in number of USB ports, their specs are virtually identical in every single way.
The A1138 was on Apple’s web site for maybe 75 days (or 120, if counting factory-configured models still in the stream); the A1139 was on sale for 180 days. Compared with other prior generations, the DLSD models may not have been on sale as long as others, including their immediate predecessors, but at least the A1139 was on sale for a reasonable amount of time.
tl;dr: locally speaking (Canada, eastern half), since finding my A1138 and A1139 in 2019, the prices for both have gone up since then as “collectible”/nostalgia demand for survivor examples has increased, but A1139s around here tend to appear for sale at least as often, if not more so, than A1138s.
Just look at the price difference between something like a IIcx and IIfx on eBay, a Quadra 610 and a Quadra 840AV, Power Macintosh 6100/60 and 8100/80AV, and so forth.
The Quadra 840AV was the high water mark for the 68k Macs. It was a delight to work with.
The Power Macintosh 6100/60 was nightmarishly, hair-pullingly slow (I had two jobs at the time — one where I worked on an 840AV, and another where I used a 6100/60 for ancillary work). The 8100/80AV felt like a half-step backward from the 840AV when our employer moved us to the former. Power Macs didn’t really begin to pull their promised heft until the 604-series Macs went on sale in ’96.