If I were to strip down to the minimum machines to cover all bases, my setup would look like this...
GEM 286 - XT Class-early 386 era (ie, 1981-1989) - In order to tweak this right, I'd need to add a Tandy 3-voice capable adapter card to run along-side the SoundBlaster for the old stuff that supports Tandy 3-voice.
CREEPING NET 486 - 386-Mid-era Pentium (ie. 1988-1997) - basically the computer the same as it is, running Windows 95 OSR 2.5 most likely to get the widest compatibility with the least speed penalty due to useless crap in RAM.
MAIN PC - Late win9x and later (1997-present) - basically my daily driver Core 2 duo box that I'm typing on right now in Windows 10 using Compatability mode and Virtual Machines as necesary.
This is assuming an experienced enough retro-system builder to make something like this and make ti all work well together - which can be tricky, or can be easy, depending on your luck what software you want to run.
The reason being for this split....
My 286, with turbo off, is like a Turbo XT, which makes the situation of running that era of games the most comfortable to run with the most accurate performance possible without being on an actual XT class machine. With Turbo on, it's 12 MHz, has a co-processor, 4MB of RAM, and a fast SCSI HDD, so the experience feels almost like a low-speed 386 SX minus the whole 32-bit code execution thing (which most games from that period ran fine on a 286). It also has a fast SVGA card and I have a nice NEC MultiSync II to connect to it for "of the period" graphics.
From my experience, everything from 1988 onward runs just fine on a 486 DX4-100, and in some ways, I favor the over-speed I get - for example, Utlima VI: the False Prophet - it just feels smoother, even though I'm aware things are running a bit too fast, but being an RPG, that does not matter so much. Other stuff by that point was throttled to run at a perfect speed, but put on anything faster it'll just overflow, or won't even run on anything modern and 64-bit. Once we get into the Windows/Direct X era games, most of the early stuff can either be run, or tricked to run, on an 80486 with not much tweaking, and a lot of it runs properly, even contrary to manuals (I'm looking at you Diablo). I just find the late 486 VLB era to be one of the best compatibility wise across the board.
Once we get around 1997, when I feel the PC became really boring, and mainstream as a hardware platform - most of the games made during that time can be tweaked to run just fine in Windows 10 using compatibility mode. I still run my old copies of The Sims, Robot Arena 2, Monster Truck Madness, Midtown Madness, and so on on my Core 2 Duo, with maybe the worst being The Sims (major graphics patching required, but after that it becomes a piece of pie and I kind of enjoy it more that way anyway). From an authenticity standpoint, it feels authentic because were no longer playing keyboard dominant/keyboard only games at 320x200 on a CRT with low dot pitch designed in a way that it makes things look smooth rather than jagged.
This is my experience. I've owned just about every generation of PC with the exception of the Pentium II and Core i-series stuff - XT Clones, Tandy's, 286's galore, more 486's than most people own computers in their lifetime, Pentiums, a Pentium Pro (which pretty much is in 686 PII/III/4 territory performance wise from my experience with a lot of RAM and a strong graphics card behind it), PIII, Pentium 4, Pentium D, VIA C7-M.....I was did this when it was junk nobody wanted, and after awhile, as much as I miss a lot of that old hardware after selling/trading/liquidating it as prices went up, I feel like that's what I'd do if I hat to cut down as much as possible and still get the full authentic experience using old hardware.