My wife got into her head that I needed to make and sample different lemonades made from fresh lemons simply because she was making popcorn. I still don't get it but it was a bit of fun anyway.
I can't say it was very extensive or entirely lemons but here's what we found out.
First, you need to make sure you have enough lemon juice and enough sugar in any lemonade you want to make. Too little of either and you don't have much of a drink and the popcorn gets cold as people wait for their drinks.
Second, Meyer lemons are much more mellow and lack the bite that your average lemon has.
Third, a bergamot orange is not a good substitute for lemons... I should have known. It does however add a very floral note to the drink if added to lemonade in small amounts.