AIO Thickness & FPI

[CypherCL]

Hey!
I tried looking up the solution to this question, but didn't really get a good answer to it.
The question, very simple:
Which radiator is more effective (if fans & price) are not a concern: 27mm with ~20-22FPI or 38mm with ~14-15FPI (Both 360mm)?

More details:
When looking for an AIO, I didn't even think about factors like thickness and FPI of the radiator at all. I thought that - basically - any AIO would perform pretty much the same (if one would use the same fans). So any ROG AIO would perform probably the same as, say, an Arctic Liquid Freezer II, if both would run 3 or 6 Fans of Noctuas.
Different Pumps probably result in different results. Given that Artic and Corsair use different pumps than the standard Asetek Pumps, they probably would give different results (You get the idea, I hope).
So when taking a look at the radiator, most AIOs feature a common 27mm radiator thickness with an FPI of ~20-22. At least the ones I checked & compared. The one I was interested in was the ROG Ryujin II.
Researching online showed me that the Arctic Liquid Freezer II features a 38mm radiator thickness (which obviously is significantly thicker, I'd say). But it features a lower FPI count (~14-15). That's only logical, as the thicker and denser it gets, the more powerful the fans have to be. 
I did not find any thread online that answers the question. Ignoring the Fans, and (probably) the Pump, does a 27mm thick radiator with an FPI of ~20-22 perform better than a 38mm thick radiator with an FPI of ~14-15 - when having excellent radiator fans (I'm going to give the Noctuas as an example, don't know which model exactly is the highest performing for radiators. Or take the Phanteks T30 as an example, they do the trick as well).

Alternative question:
Which AIO performs better (generally spoken), given either 3 or 6 Fans of (example) Phanteks T30 or Noctuas in standard or push/pull config: Ryujin II (360mm) or Arctic Liquid Freezer II (360mm)?

Both Products:
ASUS ROG Ryujin II: https://rog.asus.com/us/cooling/cpu-liquid-coolers/rog-ryujin/rog-ryujin-ii-360-model/
Arctic Liquid Freezer II: https://www.arctic.de/en/products/cooling/cpu-cooler/cpu-water-cooler/

Disclaimer: I know that money-wise, the Ryujin II (even more with custom fans) is a huge money waste, but I'm actually more interested in the theoretical answer to this question. I haven't found anything online that compares the standardized 27mm radiator thickness, and it's FPI with other sizes. So, feel free to take any other 27mm radiator-AIO as an example, if that's easier. 

Also, sorry if some things are quite weird described from my end, English is not my main language, and writing this in English definitely took some minutes... D: =)

[mike_seps]

Holding all other things equal (fin thickness, coatings, material, pipe diameter, pipe count, end tank capacity, etc). I would guess that the 38mm rad would perform ever so slightly better.  38mm is 40.7% thicker than 27mm, but 14 fpi is 36.4% less than 22 fpi. If everything else is truly linear, then you're looking at about 3% improvement in surface area of fins. Apply that 3% theoretical to real numbers (21C ambient, 86C CPU temp, 65C delta) and that 3% leads to a drop of less than 2C.

[CypherCL]

Thanks for the answer! =)