Only interested in silent, low-heat, low-power PCs that run at least a 2160p and at least two 1080p on top of that - or two 2160p. or three. Yes I know that is a lot of screen. Terrific onboard audio is useful as well because the HTPC isn't going to have room for a card.
One fanless silent video card, plus the APU (really do not want to look at non-APU systems at all) and the other PCIe slot with a PCIe x8 SSD just for boot and cache. No interest in spinning metal inside the HTPC at all, that's what USB & Ethernet cable are for.
DDR3 systems should not overclock but run at 2133. DDR4 systems should run slowest RAM that will still be usable 6 years from now, probably 2800 at lowest.
A10 and i7 and i5 and Xeon based systems are all of interest. Nothing over $1500 or with fancy cases or multiple video cards or spinning metal in the micro ATX case is of interest.