It wasn't so long ago that sights on a defensive handgun were considered, well, if not quite irrelevant, unimportant. Superfluous. After all, if you needed to defend yourself, the bad guy had to be within shouting distance, probably within spitting distance. All you needed to do was point the gun and you'd hit him.
While there are still a few flat-Earthers out there who say nobody ever aims in a real shooting, you can find story after story of cops and private citizens seeing their sights during gunfights. So it only makes sense to put the "best" sights on your handgun.
As defensive handgunning techniques have been refined and improved, so have handgun sights, and currently the type of sights occupying the top rung of the defensive/tactical ladder are what I'll call day/night sights that are functional in any lighting condition.
I think the first example of these are sights with tritium inserts that have white-ring outlines. These outlines on the sights work the same as three-dot sights during the day, while the tritium lamps glow at night. These have been around since at least 1985 when Trijicon (trijicon.com) introduced its Bright & Tough night sights. The company called them night sights even though they can be used during the day as well. However, they don't provide anything special when used during the day, at least when compared to standard three-dot sights.
Modern top-of-the-line day/night sights are designed to be the best at all times of the day or night. The most well known, perhaps because they've been around the longest, are the XS Big Dot sights (XSsights.com) and its Express sights. The front sight is rounded and features a big white circle around a tritium dot in the center. The rear sight is a shallow V-notch featuring a vertical white line.
Put the white dot on top of the vertical white line for a "lollipop" sight picture. This kind of sight picture is fast to acquire and quick to use for body shots at short distances. However, I've never been a fan of the XS sights as they have limited utility when compared to traditional notch/post sights because they are more difficult to aim precisely at distance—due to the shallow V of the XS rear sight increasing the possibility of windage errors past 10 yards or so.
The second modern approach to day/night sight design is the combination of fiber optics and tritium. For a daylight handgun sight, nothing can compare to fiber-optic inserts. They glow like they are battery powered, but at night they do nothing—the reverse of tritium inserts.
TruGlo (TruGlo.com) has been making its combination TFO (tritium/fiber optic) sights for a while now, and for years SIG Sauer offered at least one of its P226 pistols equipped from the factory with these sights. TruGlo positions the tritium capsule behind the fiber-optic rod. The tritium glows through the fiber-optic rod all the time but is only visible in low light. The end result, while being a little long, works.
A different variation on the fiber optic/tritium combo comes from Kyle Lamb's Viking Tactics (Viking Tactics.com). Its VTAC sights feature a fiber-optic rod positioned above a tritium insert—a dot above a dot on the front sight as well as to either side of the rear sight notch. These sights are taller than average sights, although not as tall as suppressor sights.
The tritium inserts are not outlined because they are meant to be ignored or just disappear during the day, when the green fiber-optic rods glow brightly. When simply examining the sights I thought they looked busy, but when actually shooting them during the day my eyes pick up only the fiber optics.
My main problem with all of the tritium/fiber-optic sights—as well as most factory day-use sights for that matter—is they've got fiber-optic inserts or big white dots on the rear sight. The rear sight is a window frame; you should be looking through it, not at it. Any dots on the rear sight just end up distracting your eyes from the important front sight.
Sights with tritium alone present a slightly different story. Most people don't train enough to have the sights line up perfectly when they bring a gun into firing position. Therefore in low or no light, there's no way for them to be sure if their front sight is properly aligned with the rear sight unless there are tritium inserts in the rear so they know where the notch is.
That's why I think Trijicon's HD sights are the best combat sights on the market. The plain black rear sight is serrated steel with tritium inserts on either side of a big U- notch. The front sight has a tritium insert in the center of a large, bright-orange or greenish-yellow dot. The dot is as wide as the front sight, so big it almost resembles the XS Big Dot, but the front sight post is of the traditional square design.
The front dot is photo-luminescent paint, so it will glow for a bit in low light. I prefer the orange front dot because it seems brighter to me and as easy to spot in daylight as a fiber-optic insert. The paint circle and tritium insert are capped with a sapphire jewel, which means the paint won't get damaged by cleaning solvents or darkened by dirt or gun-powder residue.
To me, the only thing not perfect about these sights is the width of the front sight. At 0.15 inch, it's as wide as a man's head at 15 yards away, and it fills up nearly the entire notch of the rear sight. That's not automatically a negative. At most defensive handgun distances, the big orange dot is easy to pick up, and because the post itself is the traditional rectangle, the sights can be used at distance as well. However, I prefer a narrower front sight with more daylight around it because it allows more precision.
Apparently, I wasn't the only person wishing for a narrower front sight, because Trijicon has just released an updated version of these sights: the Trijicon HD XR (for Extreme Range). It has a narrower 0.122-inch front-sight width while keeping the big rear U-notch. As a result there is a lot of daylight around that front sight, which I really, really like. Of course, because the front sight is narrower, the orange or yellow dot is a bit smaller, but it is still as wide as the front sight, which makes it pretty darn big.