I've got to agree with diizy on that the choice of OS (kernel/drivers, in particular) can make a big difference in performance. I think that OpenWrt is a great OS for wireless routers. My choices for services and infrastructure are different, based on the needs of the use cases involved.
I've run both the J1900 and 1037U in iTX form-factor boards. They run/ran on ZFS mirrors as they were critical infrastructure for me. (My APUs run on ZFS mirrors as well.) I preferred the 1037U for primarily single-threaded applications (two-core). The J1900 was faster for builds, likely because it was a four-code device. These boards handled 500-1000 mbps throughput in their applications. Looking at the Passmark single-thread measure (or other single-thread benchmarks) is important.
For a quick comparison, here are some single-thread Passmark numbers I have on an older spreadsheet:
- GX-412HC -- 473 (1.2 GHz similar to APU 1.0 GHz GX-412TC, quad-core, 6 W TDP)
- J1900 -- 536 (quad-core, 10 W TDP)
- 1037U -- 954 (dual-core, 17 W TDP)
- E3-1265Lv2 -- 1767 (Xeon, eight-core, 45 W TDP, used, in a used Lanner chassis)
- i3-7100T -- 1929 (eight-core, 35W TDP CPU, old build box of mine)
These are not recommendations of themselves, but CPUs I have to give you a quick idea of what single-core performance looks like. The choice between single-core and total performance is one you'll need to make, based on your own needs. I do not ever run "generic" services on my router/firewalls.
I'd be careful with the Atom C2000 series because of its fatal flaw and that it is often soldered down, taking out the whole unit. Since I don't have any, I haven't kept up with it over the past couple years.
My notes from a couple years ago noted the J4017 and J5005 as some options for pre-populated iTX mobos that had single-core Passmark scores over 1000. I did not pursue them as I was able to get the Lanner and Xeon for my high-bandwidth applications, and have moved my servers to the APUs for power consumption reasons, and will be moving my file server to the i3-7100T.