The vibrating needles with size of 80 mm, 60 mm, 40 mm and 25 mm available in the market.
For doing compaction, you can use any of the above size needle or bigger than it provided you are able to insert it into section for doing compaction.
When there is reinforcement congestion, using a higher size needle not possible when we cant even move it into rebar, we normally select a lower dia size needle so that it can go freely till bottom of member and can easily removed.
The compaction efforts also get reduced in terms of radius of concrete around the needle, higher size diameter have higher effective compaction area so they are immerse in concrete at great distances compare to smaller dia needle.