Nir

Why not just get a GPU and let that do the transcoding? 

Yes.... Your CPU is software transcoding, which is an intense workload for a i5-2500, a slightly modern nvidia gpu (pascal or higher) should be adequate. Used quadro/tesla cards can picked up for under $100 (US). Wikipedia has a partial list of nvenc & ndvec generation to gpu compatibility, emphasis on partial. 
 
Also the 14600KF does not support intel quick sync, the 'F' denotes that. Quick sync would also work well for transcoding video when needed. 
 
Lastly, I believe an active Plex Pass is needed for hardware transcoding. 

Are you trying to transcode 4k? Don’t try and transcode 4k… then your CPU will be plenty fast enough.
 
Storing media on a codec your devices can play is critical, especially with 4k. Direct playing media takes next to no CPU power, while transcoding 4k takes quite a lot. 

A GPU for just transcoding a single stream... for me it'd cheapest card from the latest generation that I budgeted for.
 
P400 has:
NVENC: 6th Gen
NVDEC: 3rd Gen
 
T400 or 1650
NVENC: 6th Gen
NVDEC: 4th Gen
 
1660
NVENC: 7th Gen
NVDEC: 4th Gen
 
3050
NVENC: 7th Gen
NVDEC: 5th Gen
 
4060
NVENC: 8th Gen
NVDEC: 5th Gen
 
***all information pulled from techpowerup

The Arc A380 GPU from Team Blue may also be considered, as it has the almost same capability of encoding/decoding as RTX 4060, e.g. 8K AV1 transcoding, with less limits in concurrent streams & considerably lower costs. Be aware that both of them require the latest drivers and/or Linux kernel (v6.2 or above).🤔

Yes. This is the “preferred” way to deal with this type of situation. That said, I have never done it. I never watch content any way except on my nvidia shield plugged onto my tv, so I never need to transcode my 4k content. But if you poke around the Plex forums, there is good advice there on how to handle this type of situation. 

Rule #1 is don't transcode 4k, that being said I often do... I am all for upgrading the platform, you could probably easily go i3 as long as it has intel quick sync. My unraid server has been running in a Ryzen 2700x for years along with a used Quadro k2200. If your just running unraid and plex you don't need anything too crazy. I picked up the Quadro for around $100 a couple years ago and it will handle a couple transcoding streams without issue. I would look at posting this on the unraid and plex facebook groups there are a ton of helpful users in those groups. With your budget being limited you can probably get a could deal on last gen hardware.

PC parts can last for decades... I wouldn't worry about this at all. A system built with a i5 2500 has a lot of life left in it. Knock on wood, I have never had a pC fail of old age. It certainly can happen, but I wouldn't be too worried about it. 
 
That said, upgrading may not be a horrible idea.

I want this NAS to just work, all the time (as it has for the last many years, with freenas before).
So, I going the safest as I can, with team green, and mainstream parts.
But, thank you for the input.

“Better” is frequently a useless question.  If a company didn’t think their product was “better” in some fashion or another they often wouldn’t have made it in the first place, so arguably all products are somehow “better”.  What you mean I think is better for your use case but very little is described about your use case so it’s not a very answerable question.

only good I rememver from ASUS was their usage of older systems that could be configured to a mesh network?
So I would kind of trust them more by that, but in quality etc, dunno.

Oh..... Well.... Here you go.
 
https://www.amazon.com/NETGEAR-Nighthawk-Gigabit-Support-Compatible/dp/B00F0DD0I6
 
 
 
My first idea still stands at being awesome though!  

Depends on how many devices and MU-MIMO. If you have plenty and you need wifi performance, the AC3200 if you only need to cover a small area. If you want budget and dont have mu-mimo than the older single radio 3x3 5Ghz wifi routers will still work well. If you want mu-mimo i would suggest going with qualcomm ac2600 based routers.
 
It also depends on your internet speed.

It looks like it is made mostly from plastic, and it has huge bezels. Any way, that's not the point of this thread

I'm not looking for extraordinary speakers as well so that's fine. In case needed, I can always use a Bluetooth speaker.

Thanks for the comment, I was not able to find the Lenovo and Dell new here, and the HP is way too heavy for me.
Thank you for the comment, that helps a lot!

David Tennant For The Win!

David Tennant For The Win!