Angle or match?
Because that changes the answer. You need someone to run a good match or hold a short-term feud together through ringwork and promos? It's Rollins and it's easy.
You need someone to sell a long-term angle, someone who isn't going to be all over the TV but is going to make an impact when he does and will make the most out of limited time? You go Reigns - he's the best out at the 'less with more', simply due to Heyman.
...and if you want someone who can't do either of those sets of skills, but can bleed like a stuck pig from a simple clothesline... There's no one better in the business than Moxley. Not a person.