Just a quick inventory suggests I have way too many computers too [and I was pleasantly surprised by some of the uptime numbers - my UPSs “done good” ;-)…]
You’re philosophy / set-up seems very similar to mine. I also like the approach of small, lower powered machines used for dedicated tasks, and then using older, consumer grade hardware for home built servers… I use TrueNAS core for important data, Proxmox for VMs, and a Proxmox [and soon to be XCP-NG] machine for for experimenting…
To the OP - it all depends on your use cases, what you want to do, and how much money [if any] you can allocate / justify…
Personally, I’m fortunate to have enough room in my house [including large unfinished basement] for physical space not to be a problem, and enough disposable income that multiple small machines, and using old hardware as I upgrade my workstation/gaming computers, are within my hobbyist budget… [I’ve been tempted by current generation Threadripper or Epyc, but always decide to stay away…as that’s not affordable or justified for me, especially when Ryzen 5 1600 [were, at $79] and 3600 [now, at $159 or $179] , are such good value, and ASRock B series motherboards are ~$70-90… [I live near a MicroCenter…]]
TL:DR - my collection consists of Apple stuff, and small bare-bones computers [e.g. Intel NUC] and home built machines using practical ATX tower cases [e.g. Antec], and Ryzen 5 / 7 CPUs with ASRock mboards [and ECC support] is my chosen path…
Gory details [in my defense, this was accumulated over multiple years…and I don’t often check my electricity bill 
]:
Real life/work:
- Apple laptop and Mac mini w/eGPU for important, real life stuff [e-mail, finances, taxes, personal photo and video library, e-shopping], and iPad for entertainment & reading… [I’ve used OS X as my “primary OS” since the day 10.0 was released…was Amiga OS & BeOS before that… ]
- [Company provided Windows laptop for work, supplemented by a personal, 6 year old iPad Pro for multitasking - i.e. video conferencing/meetings]
Workstations / Gaming:
- Ryzen 9 / Radeon VII, ASRock x570 Taichi : [by far my most expensive computer ever!] - for my personal workstation & gaming [triple boots Linux and Windows, but mostly Ubuntu with cutting edge kernels and graphics drivers]
- Ryzen 5 / 5700 XT for family / living room gaming - Windows & Ubuntu [depending on the games] - connected to a large-screen TV…
Small bare-bones:
- HP T640 [embedded Ryzen R1505G APU. I installed Ubuntu. Always on, and used as a desktop to manage all my servers and VMs from my home office [bargain on eBay for $120… NIB, including a 16 GB SSD and 4 GB RAM]
- 3 various Intel NUCs for services/experiments
- Pentium NUC7 - Roon audio server [optically connected to my audio system] [300+ days uptime]
- Nuc8 [Crimson Canyon - the 10 nm CPU with AVX512 and the discrete AMD RX 540 GPU - used for experiments with Clear Linux and AVX512]
- Nuc8 Core i5 - emulation gaming, random experiments… currently has a test installation of XCP-ng and and an Orchestra VM
Servers:
- home built NAS - primary file server [TrueNAS Core, Ryzen 5, ASRock Rack X470 mATX mboard, 32 GB ECC RAM, Antec ATX Tower Case, 8 WD RED HDDs…] [[250+ days uptime]
- home built dedicated backup-NAS [Ryzen 3 APU, ASRock ITX Consumer board, Chenbro ITX case, 4 WD RED HDDs…] [400+ days uptime]
- Proxmox box [Ryzen 7, ASRock B450, 32 GB ECC RAM, Antec ATX case] - VMs: Plex server, TrueNAS for shared media library, various other VMs - e.g. Pi-Hole] [150+ days uptime]
- Experimental VM box - Proxmox - Ryzen 7, ASRock B450 mboard, 32 GB ECC RAM, Thermaltake mATX case] - used for GPU pass through experiments with looking glass, other Linux distros and macOS, etc… will try XCP-ng w/ GPU pass-through on this box…