I’m relatively new to game dev.now I haven’t a shipped a game.my advise might be useless.but I recommend UE5. 
.the epic announces Ue5 is more beginner-friendly so I choose it.
the assets shouldn’t be concerned. Ue4 assets can be imported to Ue 5.only some plugins would obsolete.
and Ue5 is the tendency,you know.and getting familiar with UE needs some time. Imagine that you spent a lot time to get familiar with UE4 and some of these days you want ue5.well you have to spend extra time to get used to it.why not from the beginning chose the new one.