Is moving ionic v1 to v5 easy or moving to flutter would be better?

We have been developing an application in ionic v1 angularjs for past many years and have added much features to it.

Now as some of the plugins support have ended and facing some issues which need much work around if we continue in ionic v1.

So we were thinking to move out,
so considering to move to ionic v5 would be an easy task or not?
Or would be better to move to flutter?

I know it depends on the code, but still people with expertise can throw some light on it?

Thank you in advance.