To me the only advantage of the Katana (100 and up) over Spider V is the FX Loop present in the Boss, other than that I was not impressed with the Katana Series sound, specially distortions and high gain approaches. In the Spider V MKV1 (firmware 1.05), high gain and distortions are not so great but they a more customizable (Change Cabs, mics, post-amp EQ), and there are more possibilities for getting a good usable tone. It takes more time, but to my ears, Spider V sounds better than Katana (I prefer the SpiderV Delays over the Katana ones for instance).
However, to be honest, the best high gain sound I've heard in a practice amp is the Yamaha THR10x, every model sounds really great and is easy and quick to dial a good tone. I have one of those green boxes since 2014 and still sounds great when I record metal covers.