We are working on messenger for Android. There is a quite controversial problem: we need to show a context menu for each message bubble after some action. We want to use swipes, but it's not native behavior for Android. Are long press or additional mini-buttion near each button better?
The normal User Experience convention would say that the long press is better because (almost) all the other messengers are using the same thing.
But, I am always against the long press option, it holds the user for a few seconds for what he/she was trying to achieve.
So, the deciding factor should be, If you do not want your users to waste your time (a few seconds) for long press, you should give little options on tap of the message like Facebook Messenger does.
I think long press better because other messengers such as WhatsApp, using long press action too and users know about long press when they using their phones.
Both options are learned behaviors. I wouldn't think one is better than the other (perhaps A/B testing would give you valuable information?) but none that neither behavior will be immediately understood without teaching the user first.
Instagram has solved this problem - press briefly to comment on the right; to share the second button pops up action - showing that there are other buttons - once presses the second and eventually will use swipe - they are more friendly to man than the long press - holding, I feel out of date You can find a compromise and use both options
If you use a gesture differently than most other apps, you'll have trouble with initial user uptake - they'll install your app, fail to use it (because they expect it to work like other things on the system), and a large percentage will drop it because they can't make it work instantly.
These are learned behaviors, but they do NOT exist in a vacuum - if other apps all work a certain way, making yours different is going to be a disadvantage.