The 2 diets I recommend are Bml
http://www.bmldiet.com/index.html
and critter love
https://www.critterlove.com/
Both are widely used excellent diets. 1 you can get everything locally and the other you have to order online. Sometimes that alone is the deciding factor for which diet to go with, if you can't or don't want to order things online Bml is the way to go.
Bml is super easy and one batch lasts 1 glider about a month. It takes all the guess work out of what to feed if you follow the recipe and feeding instructions.
All of the ingredients can be found locally at grocery stores, and pet stores that sell reptile supplements. The first batch should cost around 40 bucks but once you have the calcium and multivitamin those should last you at least a year for one glider so your only restocking the grocery store items. If you go with Bml make sure to refrigerate the wheat germ after you open it, it will go rancid if you don't.
Critter Love has a calculator on their website to tell you how much CL you to feed x amount of gliders for a month.
****** IF you feed a Hpw diet that uses bee pollen, please inform your vet that bee pollen is in their diet. When vets do fecal testing bee pollen can be confused for parasites in the stool samples.
There are different Hpw recipes. One you add other ingredients to it, another you only have to add water, and another for breeders. All use the same CL salads that are fed with the staple.
Peggy of Critter Love will happily send you a sample of the diet so you can try it before you buy it. There is a link somewhere on the website for the sample.
The best diet, is the diet your gliders eat consistently well and that you can afford to consistently feed.