My go-to configurations for 386 and below.....
In General........
I prefer lay-flat XT and AT style cases - 80's style ones. Think the early XT clone chassis that look like an actual IBM (almost), or the AT clone Chassis in a similar style. My #1 favorite case - which I wish I had back, and had more of - is the one GEM Computer Products used on their whitebox 386 models. It was basically the same as the Parkview Metals cases that Compaq used on their early 8086/286/386 Deskpro machines, but slightly wider, and designed for standard full sized AT - right on down to the front Keyboard jack. But anything from that era looks cool - heck, I'll use these on 486's and Pentiums as I like that style so much.
For motherboards I tend to prefer older boards with more pin-through-hole components and thicker traces so if something deteriorates or fails I Can easily replace components and rebuild traces with nicely put bodge wires. Full Sized AT boards are my favorite from the look of it but they are not that common. They also lend well to hardware hacking for more beat up/abused examples.
For sound I tend to prefer a SoundBlaster except in XT class machines. In an XT I prefer a GameBlaster, or Tandy 3-Voice.
For peripherals and monitors, I tend to prefer 14"-15" CRTs for my systems. For anything XT Class I prefer an RGB or EGA monitor over VGA - those scanlines just make for a more "Authentic" experience that makes me feel like a Hacker in the 1980's. The biggest, heaviest, loudest keyboard possible like a Northgate 102 or IBM Model "F" or "M", and some obnoxiously oversized or weird pointing device - my favorite being the Microspeed PC-TRAC trackballs. Favorite Gamepads would be the classic Gravis Gamepad, Thrustmaster for Flight sims, or the PC ProPad 4 is my #1 though.
Typically what I try to do these days is get as much out of as few setups as possible (Though I have more)....
All the 386+ era stuff is typically handled by my army of Versa and 486 DX4-100 desktop. 486 Class is my favorite hence why I use it so much.
For all the stuff between that an XT, my 286 handles that. My 286 is a fine example of what I do with most of my vintage PC which is I soup it up heavily so all the "inconvenience" is replaced by faster, more convenient methods, while still retaining the rest of the authenticity of the experience. Basically, the feel, look, and aesthetic of the original hardware, minus things like slow MFM hdd, stressful repair sessions on CRT RGB monitors, outdated Data storage formats that are impossible to get (ZIP, Jaz, MO Drives, older Tape formats, etc...), and stuff that means I'll be spending a good chunk of my weekend fixing something rather than enjoying the machine. Mine is a GEM 286 in a AT clone case with a OCtec Fox II style motherboard, 802C87 co-processor, CPU overclocked from 10-12MHz, SVGA, SB Pro 2.0, SCSI 3GB HDD and 2X CD-ROM, and Ethernet networking over mTCP.
For XT's typically I tend to gravitate more to Whitebox clones I can get really cheap, or the occasional Tandy 1000 series model (A, SX mostly), preferring 6 or 8MHz examples over 4.77MHz, but I am fine with the original PC speed as well as that makes really really old games (ie 81-84' era) easier to run and easier to play. For floppies I Stick to 360K DSDD for the time being because I have that, but whatever is easiest. Creeping Net XT II (what was in my 486's case before it was a 486) had dual 1.44MB Floppies using DRIVER.SYS to read/write the full capacity in MS-DOS (quite a mess to deal with at that time TBH). I did that because it is just easier to minimize what data formats you use than have to go repairing and hunting down vintage floppy drives.
If I had to start over at this point, I'd probably just have two machines....with a bit of indecision....one of the faster 486's, either my Versa M/75 with Versadock or my DX4-100 in an XT case, and then a 286 with a Tandy 3-voice card and EGA, or one of the 286 based 1000s. Everything 386+ plus would be on the 486, while everything XT/AT would be on the 286, and I'd just hot-swap the Turbo off for older software that runs too fast with Turbo "on".