Their "Enthusiast" model NUC has a 7th Gen i7 (quad core, not hex), ONE TB3 port, and is fugly as the day is long. Oh, and it STARTS at $883. Granted, it has 16 GB of RAM rather than 8 GB; but the rest of the machine is REALLY lame compared with the 2018 mini.
The NUC is actually the best comparison/contrast with the Mini. IMHO its not a clear victory either way. The version here:
https://www.quietpc.com/sys-ultranuc-pro-i7 - comes in at about the same price as the i5/hex core Mac Mini (£1057 vs £1099) for 8GB RAM and a 256GB PCIe SSD.
Yes, its 4 core (8 virtual cores with hyperthreading) vs. 6 core in the Mac, and slightly slower memory, but its the 8705G with Radeon RX Vega M graphics - so whether its "better" or "worse" than the hex-core in the Mini is going to depend what you so with it - the Mini is going to win on things like Logic Pro or non-GPU-accelerated video encoding, the NUC will probably win on anything that relies on the GPU.
Its only got 2 TB3 ports (which is good going for a PC) but its also got a metric shedload of what Apple thinks are "legacy" ports, so you can hang a bunch of USB, DisplayPort and HDMI devices off it without "wasting" the TB3 ports.
Yes, the NUC is ugly alongside the Mac mini (I think it comes with a plain cover if you don't fancy the skull, though) and needs an external power brick.
If 8GB/256GB was the config I needed, and I wasn't looking for 32 performance, then I'd certainly pick the $1099 Mac Mini over the NUC.
However, if you need more RAM or more internal SSD, pretty soon, you're looking at the NUC being half the price of a Mini with the same RAM/SSD - OK the NUC specs say 32GB RAM max but 64GB may be a firmware update away, OTOH the NUC has
two M.2. SSD slots so you can put 4TB of storage there and only need to sell
one kidney. Or you could add an external SSD to the Mini, but then your
Mini system has 2 boxes plus a wall-wart.
Its not a game of "top trumps" - it all depends on what features you actually need and what capabilities you personally prioritise. Like
all Apple stuff, the new mini is terrific if you're the exact target demographic that Apple built it for, but choice is expensive.
I just think that for a computer that sells itself as being a
mini (and one of its USPs has long been the lack of a PSU brick) every time you say "just add an external drive/gpu/hub/adapter" you take away part of the point of it not being an old-fangled PCIe mini-tower.