I like the plastic ones so that you can see your eggs yes but dont use them.
Free is the best.
I am ordering recylced paper egg cartons. I really dont like them as much because they can soak up stuff if set down in a mess. But they are biodegratable.
We use whatever free cartons people give us. Some cartons are recycled so many times that both ends are colorful from marking the date in colored sharpie - then crossing it out to put a new date when the customer brings it back for a refill.
I guess it depends on your buyers.
We have a steady stream of people who know our eggs and are "regulars." They would rather we use (and reuse) free cartons because it's better for the environment. We don't have to do any anything fancy to market our eggs.
And it keeps our costs down.