If you're talking just a smigen too loose or too tight, it probably doesn't make a difference which. Too tight is probably superior from an engineering standpoint, but too loose is safer in that it'll give itself away af detectable play or a once per revolution click, motivating you to correct it. This debat won't end, and in my opinion you're looking to find the loosest zero play adjustment.

OTOH, meaningfully too tight or loose are fairly obvious and neither is acceptable, and trying to guess by spindle alone is too insensitive. Eons ago I was taught what I've come to call the Goldilocks method for adjusting bearings. First find a way to magnify play, in this case by feeling for it at he end of a mounted crank. Then if your sure there's play it's too lose, if you're absolutely sure there's no play it's too loose, but if you not sure if you can feel play or not it's perfect.