Some comments
Ryzen is a poor choice for unRAID - passthrough does not work well (there is a choice of good speed but poor graphics or good graphics but poor speed) - due to a Nested Page Table error in the s/w. Also on top of this and not even addressed in any way there are reports that Ryzen will randomly crash with Linux workloads (not Windows). Dont have links to hand but it might be Phoronix who found that. A major PITA as I wanted to buy a Threadripper for my next upgrade
I have the XL R2 and its solid. I yearn for the H440 as I think it looks better but the extra space in R2 is nice. It also has 10 PCI slots and I run 7 from mobo, a double width GPU in lowest slot AND a PCIE to 2 PCI slot expander so I can run some PCI cards. And some mobos have extra Molex power connectors on bottom (X99P-SLI does) which can foul on some cases with less room (did on my Define R5).
H440 looks good but I suspect you would be happier with the Define XL R2
Meth