25x25 is definitely a good size for 5 birds. If you can realistically afford 50x50 and think you will get more birds in the future, then sure, why not (though as others mentioned it becomes harder to cover a run as it gets larger).
You can always add on to the run later on if that time comes, have two 25x25s with a gate in the middle or something.
You can always add on to the run later on if that time comes, have two 25x25s with a gate in the middle or something.
