I’m wondering whether to choose angular or vue for ionic ?
Ionic Framework is an open source UI toolkit for building performant, high-quality mobile and desktop apps using web technologies (HTML, CSS, and JavaScript).
Ref:ionic framework
You have labeled this question as ionic-v3, with ionic 3 you can only use Angular.
It is with Ionic version 4 that you can now use other frontend frameworks such as Vue & React. However, I would advise you use Angular because it has more mature support.