safety in numbers

Hi Southcroft and welcome 

Neither option are a guarantee of no bullying,  but if you go for 4, it is less likely a gang of 3 will share the top hen position and pick on a single hen.  2 against 1 can happen a bit more often.

Having said that, if you already have your set-up and it houses 3 birds, then go with that, rather than cram an extra bird into a coop and run that are too small.  Overcrowding is stressful for the hens and can act as a trigger for bullying.

Providing dustbath areas, greens to peck, logs or branches to sit on and having a run floor that allows scratching around are all good anti-bullying precautions and make the hens very happy to boot 

That sounds like a plan    Come back and let us know how you get on.  There's always lots of advice and help offered on here 

Glad to hear its all going well