You can do with both method, you need to consider your event count though if you are free user, since you are limited to a max of 100 events.
Ok, back to the case, it could be done with a well timed repeat, which then you won't need any event. But you can also use event like 'onGroupTweenEnd' then play the other tween.
As for which is better, the event-action method is definitely better (more flexible), since you can change parameter during runtime, which is definitely an advantage. For example, you can tie a parameter to a global variable. In most use case this is definitely the best solution.
For simple case which does not need much flexibility, like title screen animation which does not need much flexibility during runtime, I prefer using non-event method, since it would save me from alot of events.