Then there are the color options. It seems intuitive that having the front sight a different color than the rear would be the best for focusing on the front sight.
Some seem to have fiber optic/fluorescent. Some have tritium/white dot. Are there any with fiber optic/tritium AND a color difference on the front sight*as that seems to be the best night/day sighting system?
Tritium night sights are useful in one very limited situation. Where you are is too dark to see the sights but the person you are considering shooting is in enough light to ID as a threat. In daylight, there is no benefit. In dusky light, very limited benefit as the glow usually isn't bright enough to add much. Some fiber optics are brighter in a lot of the dusky lighting.
So, depending on intended use, how well your eyes pick up various colors, budget, and who makes what for the Beretta I'd look at a red or light green fiber optic OR Trijicon HDs. Trijicon HD orange front sights stick out to me nearly as well as a bright fiber optic, but are also usable night sights. I think the general consensus among both competition shooters and serious professional shooters is a plain rear with a high visibility front sight, and then minor variation on that theme to suit the specific requirements of the mission. (front sight width, for example).
The HDs don't lose much in absolute accuracy potential at likely handgun ranges. The top target is my P220, 8 shots, 15 yards. The Point of Aim was just barely covering the black dot with the top edge of the front sight. Note it took me awhile to figure out the POI vs POA with these sights. Covering the target with the dot will work for up close fast shots, but when you start getting out to 50y + they were more difficult to shoot than the fiber optic/tritium combination on my P226.
I am not a fan of XS Big Dots on handguns. Much like shooting with no sights, it can be done and done reasonably accurately...but slower at distances where sights matter and no real gain over just using the slide as a reference point for aiming at distances were sights don't matter. I don't see competition shooters or professional shooters running them.