Current Saint shifter is, IMO, the best shifter ever made, it is lovely. Superb Shimano build, and stolen-from-SRAM positive feel. All the best of both companies.
Current XTR, I can only describe the shifting feel as disgusting But that's personal taste, some people like clanky, some people like superlight. They all feel broken to me. I hated the doubleshift on XTR too, so light and easy to hit by mistake. I'd rather have Deore, genuinely.
See if you can try them, even if it's just a click in a shop as they feel very different. They are of equal quality.
Absolutely nothing wrong with the Zee shifter though, it's just not as ace. Shimano don't do a bad named gear component.
Mech... Well, depends. If you want tough, then Saint. If you just want the sensible cage length etc, then Zee is fine- it's basically a shorter SLX, it's marketed and perceived a bit as a gravity product but it's not really. Horses for courses. Rocket's the sort of bike that could suit either, depending on build and pilot.
For whatever it may be worth, my Ragley's 1x10 with 32T front and I'm running a GS cage XT, seems perfect. The cage might seem a little long but I reckon it gives it better chain management- a long lever to take up slack, basically.
My SS cage Saint on the 224 struggles with an 11-34 cassette (*), it shifts and ranges fine but the short cage means the chain is pretty damn slack in the 11T. I suspect a Rocket's less chaingrowthy though!
(*Yes I know it's weird but I have my reason, and it's on saturday)