I went through numerous night sights on my S&W M&P9. One thing I learned is you need to determine what is your intended use? Self Defense (SD), Both Day and night use, target and SD. When I looked I want a jack of all trades. I never found one.
I tried the Warren Tact 2 dot, where there is a single dot on the rear sight that is amber and a single green dot in the front that when lined up the front dot is above the rear dot. Night time accuracy isnt very good because lets say you are comparing a 3 dot tritium sight, there is 2 rear dots and one front dot, line them all up in a row and you have you target that is fairly accurate. You cant align the 2 dot horizontally to know where the bullet would travel nearly as well as the 3 dot. The warrens are really intended for speed shooters in IDPA and USPDA competitions. The batman shape on the Warren Tact where too curvy for me. You could do the dave segyny versions arent as curvy but still have the same 2 dot system. One note, since these are designed mostly for competition they are design heavily for fast acquisition not necessarily for accuracy. IDPA is about time and hitting plates as fast as you can. Many of the plates arent that fair either and are usually 6-8". There is also more to the design. It is this, the rear notch is wider so you can pick up the front sight in it fast but there is slop because the front sight appears smaller and floats in the middle of the rear notch with space around it...ameriglos and most others are tighter not much slop or space they offer slower acquisition but better accuracy. I was never overly accurate with the warrens...but that isnt its design purpose nor strong suit. So there is a trade off. But since you have a glock, Warren Tacts do come in a 3 dot (my M&P at the time did have that option)...I like the Segvny (SP) version more than the Warren one in a 3 dot. You might want to consider the 3 dot for night time accuracy over the 2 dot. Oh and the Segvny over the Warren because of the busy shape of the warren rear sight.
Heinie Specialities makes a similar sight to the warren/segnvy that has a tighter rear notch so in day shooting it is more accurate than the Warren Tacts but slower. It is also a 2 dot plain with no white outline around the front sight like the Warrens. I personally like the white outline around the tritium for the front sight because it makes the front sight easier to see in the day light. Rears I can take it or leave it. In the day these are pretty nice target sights, they have a step front/serrated so target shooting is pretty accurate. And the notch in the rear sight is tight so once again must better accuracy but at the trade off of speed during the day, night as I explained accuracy with a 2 dots, isnt as good.
One extremely important question I have to ask is your vision. How good is it? Do you wear glasses? If your vision is excellent and you dont wear glasses, I like the Ameriglo operators. I did like the rears without an outline in amber and the front with a white outline around the green tritium dot. They were the best of both worlds. The ameriglos and the trijicons are very similar but with one catch...the trijicons has a white outline around the rear tritium (You can get the Ameriglos wither way as well as different color tritum)...I felt it was busy and slower to line up, this is personal preference. Trijicon makes all the tritium I believe for everyone...their sights seem to have the best brightness in that regards. I really didnt care for there shape and beveling they did with there sight.
If your vision is so so, the XS is your bet! You can line up your shot in the dark super fast and fairly on target. It is an awesome SD sight. It is however below average for target. The big dots...are big and easy to see. People tend to pick them up quick and like them, but they really arent for target. But they could work in IDPA comps quite well. So it is versatile to a degree. If you vision is bad...once again, this is your sight!
Finally tru-glo has the TFO sights a day and night high visibility solutions that they believe is the end all be all, it is a combination of a fiber optic and a tritium vial in one! They are a 3 dot designs and the fiber optic is in both front and back. In the day light...they scream at you! In the night they do well also,
I actually no longer use night sights, I have a Hi-Viz fiber optic front and a 10-8 rear, I do pretty well with them, I can sight them fairly fast and hold a pretty line on accuracy. For IDPA this is a decent setup and pretty cheap, but does nothing for night. 3 dot night for me seemed to be the best...I did like the cool factor of the 2 but when firing it was inaccurate compared to the 3 dot. Lots of missing with the 2 dots tritium sights at night.
For night you have a 2 dot, 3 dot, 3 dot TFO, and XS. I did countless hours of research and hands on, the 3 dot was my favorite...I never played around with the TFO but they seems like they could be good. Hope I helped...and feel free to ask any more questions. I have studied this area hard and long.
A few place to look, Bowie Tactical (He does ameriglo and is an excellent gun smith that does some great trigger jobs!) he is great, dave the owner is a great great guy...he has also been on Best Defense a show on I believe on the outdoor channel, he has a ton of really experience...ask him and you will get some great info. I cant say enough good about him. Also, MLE shooting sports does the warren/segvny sights. Once again, great owner and awesome customer service! All the other sights...find what you want and get it from whomever.
One final suggestion...what about a laser? If you shoot the stoc glock sights well and need a night option, add a laser. It is a cant miss option at night that offers, speed and accuracy that cant be match from any other sight system for a piston in night conditions.