Keep in mind the 12900 runs hotter than the 12700, so if you plan to do a lot of hardcore gaming, you're going to want a case with decent ventilation, and a good CPU cooler, especially if your ambient room temps are high in summer.
As Lutfij wisely stated though, we can't give comprehensive advice unless we know the intended use and what other parts it will be used with, I assume you're going to be using it for PC gaming since you posted it in this forum.
If opinions on current hardware matter to you, I was originally considering the 12600, but am now thinking of what's available currently, the 12700 would suit me best. Mainly due to more cores for future readiness. I've never been a $500 + kind of guy regarding CPUs though, just so you know. Mainly because despite being a hardcore gamer that likes using as high of settings as I can, I know full well the majority of games, which happen to be the type I play, use the GPU far more than the CPU. There's really only a small percentage of games that rely more on the CPU. So consider what types of games you play, as well as whether they rely more on GPU or CPU, to make your decision. One example of a current game that uses the CPU a lot is Valorant.
If my next build doesn't happen until the 13th gen Intel CPUs however (which is very likely), I may very well consider the 13700, especially if DDR5 is more affordable and faster than it is now, which is typically the case with new gens of RAM. Word is there will still be affordable DDR4 build options for Raptor Lake though. The good thing about the 13th gen is since Intel is fighting to become top dog in gaming again after their abysmal 11th gen, they are not just going to refresh the 12th gen with higher clocks for gen 13. They are reportedly adding "more cores, more connectivity, a revamped core architecture, support for PCIe 5.0 SSDs, and possibly even a rumored 6.0 GHz peak boost clock." On top of that the 13700 will have over twice the cache the 12700 does. It's got the same number of performance cores, but they'll be larger (read below).
Source:
https://www.tomshardware.com/news/intel-13th-gen-raptor-lake-release-date-specifications-pricing-benchmarks-all-we-know-specs#:~:text=Intel's 13th-Gen Raptor Lake,peak boost clock to bear.
So that all sounds very good, as long as they don't run a lot hotter. I say that because it sounds like they are sticking with a 10nm process, but are refining it, with what apparently is a larger performance core, smaller efficiency core design. That could very well increase heat, unless the new core architecture is more efficient at data throughput, which I'm guessing is their goal with the core architecture revamp. I'd be happy with same temps, better performance, which is what I assume they're going for.
It's understandable that Intel are swinging for the fences with Raptor Lake. They were the first to bring mixed core CPU design to PC gaming, and they no doubt want to solidify their supremacy on that front before AMD has a chance to up the ante. It's really hard to answer your question yet though, because even if we know your full spec and intended use, the prices on Raptor Lake CPUs have not been released yet. Intel, like Nvidia, don't tend to divulge that info to the public until just before they're available. So that info will no doubt come in Q4 of 2022, the time of Raptor Lake's rumored release, and may not be until sometime in November when the holiday shopping season starts. All speculation of course.