Hello everyone,

I'm looking for a suitable Access Point or RouterBoard for an ISP speed of 250 Mbit/s download and around 100 Mbit/s upload.

Disclaimer: I'm new to the whole MikroTik universe and also only have a little bit experience when it comes to networking, but that shouldn't be a problem as I'm learning quite fast. Anyway, please keep it simple

What's important to me is that the device is capable of, for example, downloading at full ISP speed while also moving around files in my own network, without the CPU going up in flames

Also please keep in mind, that I have a limited budget of around 150-200€.

I really hope some of you guys can help me. Thanks in advance!

Seriously 250/100?
That's a bit unusual proportion, was there a typo?

But if these are correct numbers, and if having the wifi AP and the router as a single device is feasible in your home, take a look at the hAP AC2.
https://mikrotik.com/product/hap_ac2
It has a quadcore ARM CPU so it should handle the internet routing quite okay at these speeds.
LAN-LAN communication in default bridge setup is handled by the hardware ethernet switch chip, so CPU doesn't even know or care about most of "moving files" like that.

If e.g. ISP entry is in the basement far away from the rooms you want wifi at, three options to consider would be
a) 2x hAP AC2, one as router (or router + wifi in that area) and one as AP and LAN-extender in the living area.
b) 1x hEX r3 as router and 1x hAP AC2 in the living area
c) 1x hEX r3 as router and 1x cAP AC in the living area for ceiling mount.
I'd be leaning towards option a) because of the better CPU in the hAP AC2.

In any case, please make sure to upgrade to the newest long-term RouterOS (6.44.5 as of today) and then upgrade board firmware from within the new RouterOS.

250/100 is correct. I'm from Germany and that's nothing unusual here

A friend of mine also told me to go for the hap ac2 so I ordered it. Thank you for you response

Good luck, hope you'll like it!
(And well, over here I think I'd need to have like 750 download to get 100 upload, thus the surprise. :p)