Some of the linux isos are rather porky these days. Just imagine at a 300 baud donload speed!
I started with Debian and apart from one fruitless attempt at Redhat a long time ago, I've stayed with Debian. I once downloaded 14 CD images over 256kb/s ADSL and that took 6-8 hours for each disk, but these days I always download a net install iso and then get only the packages I need. I started with Debian when the package manager was dselect, prior to apt, et al being available. dselect still survives as the underlying layer for apt. Using dselect makes Chinese water torture a pleasant experience!
One unfortunate thing that's going on now is that some kernel development is not being tested against kernel ax25, and ax25 is breaking. I've just set up an old Pentium 4 to run some old (late 80s) packet hardware. To avoid some recent kernel ax25 issues I've gone back to Debian Jessie with a 3.16 kernel and it's working fine. I wouldn't do that for my desktop system - Debian Buster (Testing but just on due for release) - but for an aprs-only machine the old version and kernel is fine. I'll likely leave the ADS-B system on the old RPi with battery back up, but the rest of the radio stuff will go to the P4.
Speaking of the RPi (and dongle), I've been playing with agc/gain settings to assess performance changes. Previously I had agc selected in the dump1090 configs but it's now on 48dB. I initially knocked it down to 30 and promptly saw about half the planes disappear so I stepped up to 45 and now 48dB, and for the last two settings I "think" I'm seeing the same range/plane count as with agc set. It's quite difficult to make really meaningful tests when the playing field keeps changing. What I have noticed is the range of RSSI has changed from about 20dB with agc, to around 30dB with fixed gain. Not knowing how the internals of the dongle work means I don't know how I should interpret those numbers.