I started with a Raspberry Pi 3B, and it worked great. The 4 would work even better. Going that route greatly simplifies the install, you just burn the image to the Pi and start configuring.

I recently switched my HA server over to an old laptop I had that wasn't doing anything so I could put the Pi to use as a Kodi front-end to my MythTV DVR. We recently "cut the cord" and dropped cable TV, so I had to dig out the old HDHomeRun digital tuner boxes and put them back into service recording over-the-air TV. I probably would have just bought another Pi if they were in stock anywhere...