I have no personal experience with the Sendero, but its a very rare thing to here of one that has accuracy issues. Lots if guys here Love em.
I'm a Winchester guy myself. I'm an admitted Model-70 Freak, and obviously I'm bias in my recommendation of the Winchester Coyote.
I load for my cousins 270WSM Coyote & its a true 1/2 MOA rifle. It's flat out Awesome. I've held some, shot quite a few, & have absolutely nothing but good to say about them.
I've never seen one that didn't shoot sub MOA groups.
The issues you may have hered about were mostly concerning the Walmart special, shadow model. And quite a few of those were mostly rumor simply because Winchester was closing the doors. Some however were true, but the Coyote is not included in those rumors. I'd buy one in a minute with confidence. Plus, most smiths prefer the push feed, over the controlled round feed -pre64' style extractor claw, for ease of customising. It's almost the exact same as the Rem 700 style bolt. The difference is Winchester recoil lugg is integral (meaning one solid piece with the action), + a 3 position safety. REM is not integral, & they have a 2 position safety.
Rule #1
You get what you pay for, so DON'T buy guns at Walmart. Especially the cheapest model made, & expect them to run with the big dogs. Unless its a complete fluke, they simply, can't & won't be able to, as a whole.
Rule # 2
There are some absolutely horrible rumors about Remington QC & Warranty depts. currently in circulation.
Don't belive all that you here. If there was a major accuracy issue with the Sendero, the Rem fans on this board would be STEAMING MAD! I'm guessing most of the rumored issues are on thier cheaper models, & the issues (if any) with thier higher end models are rare.
Both are highly customizable. Both have a HUGE selection of aftermarket parts, & accessories. Both models mentioned are known for incredible accuracy.
If you had to pick a quandary to be in, you picked a good one. There's no wrong answer. Get what you like most.