Which is the better Multiboxer CPU i9-9900k or i9-9920 and why?

[Chumbucket]

Heya. I'm trying to get down the fundamentals of designing a new rig for multi boxing and thought this comparison could generate some insights. I'm thinking of getting a single Nvidia 2080 ti graphics card but could use some recommendations on a CPU, motherboard and ram. My current rig is not holding up to the new system requirements too well and I'm looking for an upgrade that will last a while. I realize there is a large disparity in price but for the sake of discussion which card will perform better multi boxing (if at all) and why?

The i9-9900k is 8 Cores, 16 Threads @3.6GHz, Coffee Lake. This Cpu has a 10% faster single core speed and a 9% faster quad core speed than the 9920x according to userbenchmark.com
Release date: Q4 2018.

The i9- 9920 is 12 Cores, 24 Threads @3.50 GHz, Skylake.
This CPU has a 37% faster multicore speed and a 44% faster OC multicore speed than the 9900k according to userbenchmark.com.
Release date ≈ Q4 2018.

The 9900k is considered a "gamers" cpu but with the unique multi instance use of WoW for multi boxing I'm not sure if more cores will improve performance over a slightly more overclocked gamer's cpu.

Thanks in advance.