First, it is a really well-tested and tried construction. SLRs have been around for a century and most people associate them with the word ‘camera’.

A technical advantage of modern SLRs is that they provide a direct, optical view from the lens. So, latency or low-light noise in the viewfinder is not an issue. This is not the case with some mirrorless, bridge, and compact cameras.

Their bigger size provides space for more buttons. This allows for faster and more precise manual controls.

But they have an edge simply because of being the most wide-spread type.

The two most popular DSLRs (Canon EF and Nikon F) have over a thousand lenses available.