What is your budget?
There is typical red-dot technology, like the Romeo5, Aimpoint T/H series, Trijicon MRO, among others. These usually feature battery life measured in years. Holographic sights use a different technology to project the “dot” and will usually come with a more complex reticle like Eotech’s circle-dot reticle. The trade-off for holographic sights is a much shorter batter life. Some people with astigmatism sometimes have issues with red-dots as they appear as a slash rather than a dot (not common, but it happens), those folks have good luck with holographic sights.
Some of the red-dots come with mounts, some don’t. So when buying be sure to check as that may affect cost/price.
The Romeo5 is great, I have it on one of my rifles and they seem to have a pretty good reliability rep. You can usually find it under $150.
Holosun also has some good models in the budget optic price category with very good reliability. They have both red-dot and holographic models available. I am unsure about night-vision or magnifier compatibility on these.
If you are looking for “duty-grade” optics, like for hard use, then have a look at the brands below. They have been tried and tested by LEO/MIL for many years with outstanding service records.
Aimpoint has several models, ranging in price from (IIRC) $400 to $800. They have extremely small/lightweight versions that are still extremely tough and also slightly larger/bulkier models. They should all be compatible with a magnifier if you want to add one at a later date. Also night-vision compatible.
Eotech has several models that are Holographic, and have long been a gold standard with a large viewing window and the “donut of doom” target reticle. Prices (IIRC) are $500+. And they also have magnifiers available. Also night-vision compatible.
Trijicon has a few models around the MRO series. Price (IIRC) is $400+. Very large window to see through. Not all models are magnifier compatible, so if thats important to you, be careful which you pick. Also night-vision compatible.
In general, I dont recommend any of the really budget red dots like you might find on Amazon for like $50 unless you really are just testing to see if you like the idea of a red dot without dropping a ton of cash.