There's a personal aspect to it as well. I mean, sensibly, I could get rid of my LCIII because I have an LC475 - but I bought the LCIII whilst at university in Germany, so there's sentimentality to that one.
Macs I have
Macintosh SE (my first ever Mac, I bought it in Orpington, second hand for £400 in 1992, my first year at university.
Macintosh LCIII (bought in Hamburg, and since upgraded to an LCIII+)
Macintosh SE/30 (the greatest Mac ever)
Macintosh Quadra 650 (bought for an experiment, not used so much any more because…)
Macintosh LC475 (upgraded to full 040, heatsinked, 68MB RAM, and probably my most used 68k Mac now)
Macintosh IIci ('bought' in the last few years, where 'bought' is 'recovered from a pile of junk in a barn that the farmer was clearing out'. There were two, both more or less working, one very scruffy. I sold the scruffy one and the nice one is working perfectly now.)
Powerbook 100 (from mg man, thank you, and since upgraded with wifi. I sometimes use it for work, and I have pondered replacing the battery).
PowerMac G3 (upgraded to G4, and which broke half way through a development project. I'm thinking it might have forgotten how to use its G4 upgrade - so now I need to find a 400MHz G3 processor if I'm going to get it working again)
PowerMac G5 (dual processor, I need to replace some of the RAM which has gone mouldy. But, even with only 2GB RAM, I was able to finish the project that I started on the G3).
2011 MacBook Air
2011 Mac Mini
2011 Mac Pro (dual 6 core 3.42GHz, 128GB RAM, stupidly large graphics card, many terabytes of SSD)
2020 Mac Mini (my first Apple Silicon Mac, and wow! it even scorches the Mac Pro - and with far, far, less memory and much lower power consumption)
2022 MacBook Air
Those are just the Macs, and just the ones that spring to mind. And the bold ones are keepers. If it's not bold then it may go at some point. If the offer is good enough!