Marin Rift Zone 29 2 vs Specialized Stumpjumper Comp Alloy?

The new rift zone is sick, I would take one over a stumpy, especially since the new stumpy is on its way soon.

As one of the testers in that group and a fan of the Stumpjumper, the Rift Zone blew me away with how well it rode. I would've taken it home to continue riding if it was an XL rather than a size Large. Still, the geometry was great, the suspension was pretty much equivalent between the two, and I think the wheel/tire combo was my only complaint on the Marin. 

If you are new, Just ride the thing first.

If your on a budget dont worry about upgrading anything right away on these 2 bikes. Think of each part having a health bar, vital test rider will rapidly delete bar, you riding prob wont move it. This a very dumbed down reply. I have my own strong opinions people may or may not agree on hub,casing,stack,bb height, brakes etc.etc. But it can be a bit much, thats why just get out and ride is usually the best answer.

My 2021 Marin wheelset with vee tires has been great, with some love from a cheap spoke wrench 11spd,27.5, Tubed, wirebead, medium compound is not what was tested or specced on new rift zone

The stock ones will get you out and riding just fine and for getting into the sport they’ll work great. If you find yourself needing to upgrade, I think a set of Reserve 30 AL wheels would be a great option for a well priced, reliable upgrade. For tires, I think any of the major brands Trail or Enduro casing options would be a noticeable improvement if the stock tires feel a bit sketchy. 
 

Either way, the stock setup will get you really far!

What JS said, ride the bike as it is, if you starting out in MTBing than the stock rims will last a while, and when you wear them out upgrade then. Same for the tires, run the stock ones and when they wear out upgrade to a trail type tire that your LBS carries, something like a maxxis minion dhf for the front and dhr for the rear. Plenty of good tire brands all with good grip and casings such as Maxxis, Schwalbe, Michelin, Vee.

I agree. If you're new, I would recommend a "replace it when you destroy it" mentality for upgrades instead of a "upgrade now for performance gains" mentality. New riders are typically hard on equipment and in the process of riding your first modern mountain bike you'll learn a lot about which sort of parts you like, want, or need. There are a dizzying amount of options for any MTB part, and the longer you ride before you buy something, the more you'll know. As others have said, either of those bikes should be great for you right out of the box.

Just rebuilt San Quentins rear wheel after 3 years that kinda, sorta, notta had same parts. Volume//Stiff casing/Puncture resistance was great. Zero Maintenance, Zero Cost rear hub was great. Grip 5/10 POE 1/10. Rim looked great so I ordered new spokes/freehub and built myself. Definitely not disagreeing with the testers in any way, thinking they halfway understood that.