Mirrorless systems are a synergy between what’s best with point & shoot systems, i.e., their compact form and what’s best with interchangeable lens systems, i.e., the ability to use different lenses as you need.
Mirrorless systems could easily be tagged as the best digital cameras but for the lack of an optical viewfinder. They have an electronic viewfinder.
That said, modern mirrorless systems such as the Sony a7R III and the Panasonic GH5 and GH5S have completely blurred out the difference in terms of reliability and accuracy between a normal optical viewfinder and an electronic viewfinder. Refresh rates have gone up and so has color accuracy.
You may also like to check out the current top 10 selling mirrorless cameras.