What would you choose between 'clean code but just completed half of the tasks' or 'messy code but completed all of the tasks' ?

Strict dead line -> messy code, refactor later.
Flexible dead line -> clean code

Depends on my pay...

Clean code if the project is not expected to die any time soon. There will be more direct or indirect work to be done if you start with messy and the next step is not to clean it up.

I don’t know how to write messy code. IMO messy code happens when many authors added something within a long period of time. If you’re the only author and you write messy code even in one take, there is something wrong with you. You may not be a bad engineer though. just learn how to listen to yourself and determine if you’re tired or not. Improve your work/rest pattern.

The second one pays better.