Hardware.

90% of users don't care about software since most of them won't even use majority of the functionality of a smartphone. Phone calls, camera, e-mail, web browsing, some gaming, and handful of apps is all majority of customers need. In fact, there was a study shown that a LARGE majority of users don't do anything to their phones. They just use it out of the box. No Nova launcher, no real customization, etc.

Phone companies know this. If it was all about software, we would still be seeing LCD screens, LPDDR3 RAM, non-3D NAND flash storage, etc. to save on costs.

Yet, Samsung singlehandedly made the entire high-end smartphone market switch to OLED 18:9 bezel-less phones.

LG, Apple, Google and the big 4 Chinese phone companies have all rushed to sign long-term contracts with Samsung and LG for their displays, NAND chips, and high-end RAM and there is currently a huge shortage.

When a normal dude walks into a phone store, he will buy an iPhone if he is on iOS, or the S8 if he wants an Android. He doesn't care about 'stock android' or any of that shenanigans.

With that said, for me, both matters. I lean towards hardware since I can do things to phones that basically makes it stock. I personally like Samsung because they offer some pretty important software implementations that stock Android doesn't currently have (HD Audio processing, KNOX).