I recently replaced the KE-4 with a Kilimanjaro (like half a WEL in PSS content), which when biwired with Mont Blanc makes for a cable almost identical in geometry and awg to the tree series, and with overall PSS/PSC+ metal content that places it between the Redwood and Wild Wood. I’m going off memory but I’d say it’s at least incrementally better than a Redwood. The KE-4 is now making for a great dedicated supertweeter cable, too.
I think you’d want a Wild if you’re concerned with getting close to the very top performance, but the list prices are stratospheric. A good used deal is bound to come up. The Redwood is really nice sounding but I think it should be priced lower for what it offers ($8800 list for an 8’ pair is too much for a mostly PSC+ cable). One thing about the newer AQ tree series -- cosmetically, they’re on another level beyond the prior counter-spiral series.
I’ve also been upgrading my interconnects to Wind/Sky/Wild level, and those have been fruitful upgrades so far -- the resolution difference between the Colorado and a good PSS silver IC are fairly striking.