That question is as old as baseball itself. And the answer -- assuming there really is a definitive answer, which is debatable -- has changed and evolved over the years. At one point, for example, most teams didn't have logos on their caps, an approach that now seems ridiculous. And for a while, many teams were wearing powder blue on the road, instead of gray.
But we live in 2016. So what constitutes a good baseball uniform now? Here are some thoughts:
1. The cap. You need a cap. That may seem obvious, but keep in mind that the baseball caps weren't invented to keep the sun out of the players' eyes or to help tell the teams apart. They were invented because a gentleman in the mid-1800s would never appear outside with an uncovered head. Now that we're in a more casual, sunglasses-equipped era, why should a player have to wear a cap on a 95-degree afternoon (or even an 88-degree evening)? Why should the players in the dugout have to wear caps, or the players in the bullpen?
Because the cap is the anchor of the uniform, that's why. You're on a baseball team, you wear a cap, period.
And what should be on the cap? A few teams have the team nickname (A's, White Sox) and a few others have a logo illustration (Indians, Orioles), but most teams use the initial(s) of their home city: NY, SF, C, W and so on. All of these approaches are fine by me.
Meanwhile, don't forget the underbrim, which, as its name suggests, is the underside of the brim. Back in the day, it was green. Then it switched to light gray. Nowadays it's black. No contest there: Green is the way to go.
2. The jersey. Every single season, there's a play where a ground ball hits an infielder in the chest and somehow ends up inside his jersey, or a batter who gets hit by a pitch that somehow gets lodged in his jersey. All this could be eliminated if teams switched to pullover jerseys instead of button-fronts. Think about it: No other sport has button-front shirts. Why bother with all those buttons? Because baseball already tried pullovers in the 1970s and ’80s and they looked like crap, that's why. A baseball jersey should have buttons, period.
And what should be on the jersey? A simple left-chest logo on the home jersey, like the Yankees and Tigers wear, is fine. Otherwise, the protocol is simple: You wear your team name at home and your city on the road (because, as my father explained to me when I was very young, "If you're a guest in someone's house, be humble and just tell them where you're from"). If you absolutely have to wear your team name on the road, well, OK. But geez, don't wear this at home, or people will start calling you the Texas Texases.
Solid-colored alternate jerseys? I don't much care for them, but the kids seem to like ’em these days. Try to restrict them to one particular day of the week, so they don't get out of hand. And don't win too often while wearing them, or else someone will start getting ideas about wearing them all the time because they're a good-luck charm.
3. The pants. Baseball pants should have a belt. Why? Because we tried elastic waistbands for a while and they looked like crap, that's why. Baseball pants need to have a belt, period.
4. The socks. Socks are sort of at the mercy of pants: If the pants are worn too low, you can't see the socks! Unfortunately, despite all the regulations regarding baseball uniforms (you have to wear a cap, everyone's sleeves have to be roughly the same length, blah-blah-blah), there are no rules regarding baseball pant length. As a result, we now have a sorry mishmash of some players with their cuffs hiked up high, most with their pants down at their shoe tops and a few who can't decide. (The poster boy for this last group is Mets third baseman David Wright, who goes high cuffed for day games but low cuffed for night games.) And even among the high-cuffers, there's a further mishmash: Most high-cuffers wear solid-colored socks, but a few wear stirrups. So much for the uniform being uniform -- it's a mess out there!
The easiest way to clean up the mess is to impose a simple rule stipulating that pants can go no lower than mid-calf. That will eliminate the footie-pajama look and give us a nice display of colored socks on the diamond.
And why do we want that? Because that's how baseball is supposed to look, that's why. Heck, how do you think we got team names like the Red Sox and White Sox? A baseball team should show its colors, including those on the lower leg, period.
5. The shoes. Some teams like to wear blue shoes, red shoes, orange-trimmed shoes, but forget about all of that. Just wear black. Why? Because black goes with everything and provides a solid foundation for the rest of the uniform, that's why. Baseball shoes should be black, period. (Unless you're the A's, in which case they should be white.)
And there you have it -- a good set of uniform rules. All of which are made to be broken, of course.
Paul Lukas has been writing about uniforms for ESPN.com since 2004.