If you have uncorrected astigmatism, you may have trouble with a reflex red dot sight, whether it is the RMR type or tube type. Astigmatism can cause a varying degree of distortion of the dot or even cause multiple dots to be visible. Try looking through some red dot sights to see if this will be a problem for you.
Primatic optics with etched reticles are typically a bit bigger than most RDS but seem to cause less trouble for people with astigmatism. As do holographic sights. But true holographic sights are not very common. They are made by EOTech and Vortex only, although some other makers may label their reflex sights "holographic". Red dots use an LED emitter to bounce the dot image off of the angled front lens of the optic. The lens is a critical and necessary part of the sight. Holographic sights use a laser diode to emit light that is bounced off a series of mirrors and diffractors to collimate the beam and project it out in front of the optic. They work even if the front lens is missing. They also have the advantage of allowing a smaller dot size (down to 1 MOA) and the dot is not magnified if you use a magnifier in conjuction with the holographic.
For refex sights the dot is magnified by a magnifier. A 2 MOA red dot sight remains a 2 MOA dot, because the target image is magnified proportionally with the dot. But the dot looks bigger and the magnifier makes irregularities in the dot more noticeable. With a holographic sight and a 1 MOA dot, the dot does not get bigger with a magnifier. So with a 3X magnifier, the dot now effectively becomes a .333 MOA dot with regard to the target, which is nice. But holographic sights are considerably larger than compact red dots, have a much shorter battery life, and are expensive ($400+).
Pretty much all rifle scopes will have an adjustable diopter that will allow you to add or subtract 2 diopters or more of spherical correction. That should help you focus the reticle even if your optical correction is not perfect. And with a riflescope, red dot sight, or prism optic you do not have to worry about aligning a front sight post or blade with a rear sight notch or peep. That itself is a big advantage over open sights. When shooting with a 1X prism scope or red dot sight, I keep both eyes open and focus on the target.
Most red dot sights offer no magnification although there are exceptions. Most can be used in conjuction with an additional magnifier placed behind the RDS on a swing mount that allows the magnifier to be swung to the side. Of course, that adds additional complexity, weight, and expense, but is a reasonable option for those who want the rapid target acquisition and the ability to shoot with both eyes open that an unmagnified red dot offers, with the ability to provide magnification to shoot out to 100 yards and beyond for those of us who need it. There are also low variable power optics (LVPO rifle scopes) that have a true 1X low power which allows them to be used for short distance shooting with both eyes open, but provide magnification typically up to 4-8X for longer range work.
Personally, I prefer "micro" sized red dot sights for ranges up to around 100 yards, but I have also used relatively low power fixed magnification rifle scopes (3X), and red dot sights in conjunction with a 3X magnifier. I have had very good luck with the SIG Rome 5 and now have three of them. I have a Burris 3X magnifier that I like pretty well. I have also had good luck with a Vortex unmagnified 1X Spitfire prism scope with illuminated etched reticle. I am just starting to work with a Vortex Strike Eagle 1-6X24 LVPO. If and when I am inclined to shell out the big bucks, I will likely spring for an EOTech Holographic.