I already replied to this thread but forgot what I wrote, just to be sure I want to specify this:
Depends on who you are, which means what techniques you use, how you prefer to use the bass and how big your hands are.
Further more it will depend on what you play.
Yes, I do believe that in some instances for some people a 5 string will be easier to play than a 4 string, for instance if you prefer to play vertically on the fretboard rather than horizontally.
But If you do prefer to play up and down the fretboard rather than vertically a 4 string in most cases will feel more comfortable though.
Finally if you are in need of the extra low notes a B string can deliver and at the same time is in need of a high G string you really don't have much choice but use a 5 or 6 string bass.
In that case it will not alone be easier to play a 5 string, it will be straight out impossible for you to play a 4 string.
I don't believe there is any objective and general conclusion to your question though, it really depends.
Personally 4 strings is what makes most sense to me with how and what I play.
But that's just me.
Playing a 4 string is like playing naked IMO.
So...totally better than a 5 then?
You should try a 2 string. I bring mine out for a couple of songs a set. It's fun.
A 2 string bass might make him turn invisible.
I would advise to be cautious with that.