Those CPUs are 2 generations and nearly 2 years apart.
The two you suggested are from the same series, and released at the same time.
Then why did you suggest they use a worse CPU than what they already use, from the same generation as they already use?
... From what? Are you suggesting it's an upgrade over the current i5 or the current i7? Because again: fewer, slower cores. Yes it's 2 generations new
You don't really seem to get my point.
i7 7700K and i5 9600K might in theory be (by Intel's marketing nomenclature) "two generations" apart. But they literally have the same IPC. Advantage i5: Meltdown fix and soldered heatspreader.
My point therefore is: 6 cores are on par with 4+4 cores. Clockspeeds are roughly the same, probably even leaning more towards the i5.
Since the i5 8500B (6 cores) and the i5 8209U (4+4 cores) have the same IPC they will roughly be on par with each other (i5 8209U at a disadvantage because of lower clock speeds, ok, take the i7 8559U then) and even more so the i7 1068G7 that actually does have
significantly higher IPC and better graphics so this one really would be an upgrade compared to the i5 8500B and the i3. I would chose this one anytime over the i7 8700B despite having fewer cores because the overall package is better (GPU, IPC, Spectre+Meltdown fixes, WiFi 6, Thunderbolt integration).
Cache, RAM... what difference does that make? In the end most of these chips come out of the same factory with the only differentiator being the socket and TDP and some tweaks here and there (a few Mhz higher RAM clock, bits more Cache). "Low power CPU" is meaningless as you can easily up the TDP.
The i7 8559U scales well with TDP. In these Intel NUCs you can set the TDP as you like and you are only constrained if you leave it at very low TDP, like 15W. But at 28W or even higher, thinks look very different (if you have enough cooling, but no issues here with the Mac Mini).
Just think about it: The freshly released MacBook Air can drive the Apple XDR display, but the MacMini cannot.
