This version is used by a majority of Chrome users and is a result of extensive testing in other versions of the browser, making it the safest and most stable version of Chrome.
Chrome beta is mostly stable, with a few minor bugs hampering its performance at times — which are then fixed before the update is rolled out to the stable build.
Beta is the final stage of testing the update, gets the final tweaks in user interface and gets tested for bugs before it is released to the wider audience on the stable version of Chrome.
The Dev version of Chrome is more prone to crashes, errors, extension compatibility issues and more as the update on this version is still in its early stages with lots of bug fixes arising and pending fix.
This version is basically used by developers to test compatibility issues. Most of the updates you see here won’t ever make it to the stable built.