They are all Chromium-Based browsers.
- Opera has performance features, marketed to a gamer audience. You do not need to worry if some tab is eating your CPU. You don't need to install an extra ad-blocker to block potentially crypto-mining websites;
- Opera has built-in interface for social media like Twitter; As a developer, I'm completely not a fan as it adds bloat. But might be useful for someone who works heavily with social media;
- Opera doesn't have profiles, which is a big NO. For my use cases, profiles are interesting if you have multiple Google, Bitbucket etc accounts for personal and work use. Very useful if you need to log in with non-personal enterprise accounts too.
- The biggest plus in Brave is that it has built in blockers, which help with performance; Brave wants to fight the ad and tracking economy.
- Brave wants to promote its "Attention Token" (BAT), which aims to be a monetization alternative;
- BAT is a cryptocurrency, and does some fair usage of your CPU to work (EDIT: not anymore. BAT is now farmed with browser ads);
- Brave makes compromises for privacy. Some behaviours are limited. For instance, they don't have an internal PDF reader, their dev tools also has features cut from the original Chrome Dev Tools. Some files had no syntax coloring, for instance;
- (edit) Brave shows its own ads in notifications (can be disabled) and on its new tab. A bit weird.
- Firefox feels considerably faster than any other Chromium Browser, since its a different revamped engine;
- Font rendering is a bit different;
- IMHO: The main downside on Firefox are its Dev Tools. They used to be considerably worse then Chromium's, but now are much closer.
Edge is my main browser since launch. I have tried both Brave and Opera before in order to replace Chrome, but they didn't stick.
- Edge is faster than Chrome. I don't really use side tabs, share, or collections but they are interesting and non invasive; Its reader mode and screen capture work well;
- I didn't miss anything from Chrome's DevTools. And they actually add more things on top of it;
- Addon compatibility is great. If you can't find the addon you want in the Edge store, you can install it from the Chrome store;
- It sleeps inactive tabs and it shows tabs separately on alt+tab (can be disabled);
- Although Edge is clean, it seems it walks in the way of feature bloat. It has added a "detect store coupons" feature that didn't catch well for me;
My main goal with replacing the main browser was to have the same featureset Chrome had, but with higher performance, and maybe slightly better UX. So Edge won me.
The second contender to me, very close, is Firefox.
If you don't need to use profiles, Opera might be interesting.
Brave might be your case if you prioritize leaner website loading (less tracker requests) and you want to help fighting the surveillance economy.
Edge is a straightforward replacement for Chrome, its unlikely that you will miss anything from Chrome on Edge, especially on the DevTools department.