First: Louis is cool.
Had to get that out of the way. .

Personally, I’ve come to expect a noticeable diff from both series/parallel wiring and juggling impedance taps matched and mismatched.
How much of a diff and your preference depends on the specific amp, output transformer, speakers, and what you’re going for, so you do have to try everything yourself.
That being said, I prefer the biggest available tap for the cleanest sounds.
Most of my fave dirty/colorful stuff is impedance mismatched and series wiring.

My normal best of both worlds strategy for tapped OT 8 or 4 and 2×12 is two 16 ohm speakers in parallel for a total of 8 ohms; the 8 ohm tap gets used for the loud and clean stuff, the 4 ohm tap for the less efficient more colorful performance.

It’s a tricky question, relative sonics between taps on a guitar amp because the negative feedback doesn’t follow the taps around.
Normally the amount of negative feedback is some ratio with the load impedance.
When you change taps, regardless of whether or not you change speaker impedance to match, you’re still changing two things at once; the ratio of primary to secondary windings in the OT and the negative feedback.
Who knows which one you’ll react to or prefer or why?

End of the day, I think the big winding, closest to primary does the best job overall, but I just love 4 ohm Fender tranny’s too.

So it’s not like “16′ oooh. .
The tap, the feedback, the speaker impedance and wiring scheme all need to be tweaked in the same direction, optimized to your application.

No individual contribution from any of those variables is significant enough to matter compared to impedance mismatching which noticeably skews the amp’s EQ and output power.

Anyway, thats about as far as I got with it.

Mostly these days I prefer the lower powered, tube rectified, mismatched 8 ohms on the 4 ohm Fender thing.
Or the HiWatt @16 ohms
; )