I think it also depends on the opponents. When you're flavor of the week for Cena to put you down, as was the case for about a decade, it got boring fast. I think they've done a decent job of mixing it up now. I've come to enjoy Reigns a lot since he became a full blown asshole after WM32, and I think a lot of his feuds with heels have been pretty good.
Rollins believed he was the better man.
Rusev was sick of Reigns being an asshole towards him and attacked him. It just escalated from there.
Owens was basically trying to prove himself the better man. That fed into the matches themselves with him constantly upping the ante.
Strowman was just trying to murder him.
The face feuds kind of felt different too with Reigns treating both Styles and Taker like shit.
It helps Reigns bumps well, but also that the stories don't have the typical "monster of the week" feeling to them. He's more of a Rock type character than the stereotypical Hogan/Cena where they just dominate constantly whilst going through one opponent after another.
Funnily enough, I think the only feud since WM32 that I haven't liked of Reigns is the current Cena feud. It doesn't fit the asshole I've come to know in the past 18 months and so feels inauthentic. There'd be no "shoot" wars with him because he'd just attack you once you disrespected him. Yet he's here trading verbal jabs for four weeks or whatever.
I think the mistake WWE makes sometimes is that they default to what they think is supposed to work, rather than allowing the personalities to organically clash with each other. Kind of how Strowman earlier in the year walked away from Lesnar, which felt weird, whereas he's just attacked him recently. And that's hype because it's what you expect from Strowman. Part of the interest comes from seeing two different characters interact. You can kind of guess how they will, so you look forward to seeing it. I know the only reason I was looking forward to Cena/Reigns was because I thought Reigns would just attempt murder within the first interaction or something. Instead they've somehow managed to water him down to fit the same template of most Cena feuds.
