I own several MK pistols. Some have a scope, some have red dots, some use open sights.
First, decide what your needs are.
A scope is more precise in longer range accuracy.
A red dot can allow faster target acquisition, and is used a lot for "speed" competitions. It is also used for casual plinking etc. Dots come in different sizes,, such as 3MOA,- 6MOA. This means that the dot will cover a 3" diameter at 100 yds, or as much as 6" at 100 yds.
I like red dots a lot,, but for longer distance serious accuracy,, a scope wins.