I have used mitmproxy for performing web application pentest for years.
If you want something to create/intercept/edit/tamper/replay requests, this is your tool. If you want to script any of those things, this is still your tool.
However, burp comes with a lot of bells and whistles that don't make a lot of sense to build in to mitmproxy, but you can script yourself. For example, there is no intruder, spider, or scanner tool. But, they have an easy to use interface to write scripts that will be run on every request you make, or individual requests.
Or, you can just pass all mitmproxy traffic out to burp and get the best of both worlds.
If you want something to create/intercept/edit/tamper/replay requests, this is your tool. If you want to script any of those things, this is still your tool.
However, burp comes with a lot of bells and whistles that don't make a lot of sense to build in to mitmproxy, but you can script yourself. For example, there is no intruder, spider, or scanner tool. But, they have an easy to use interface to write scripts that will be run on every request you make, or individual requests.
Or, you can just pass all mitmproxy traffic out to burp and get the best of both worlds.