I personally have never understood why this would be a one or the other choice at all (though a lot of people ask it). Despite physical similarities, flying squirrels and sugar gliders are very different animals, with very different needs and behavior. Which have you done more research on? Which are you more prepared to meet the needs of? Is there a vet in your area more experienced with one or the other? Depends more on what you're prepared for, than the animal itself.
I have done more research on baby squirrels but i have people telling me that i should get a sugar glider plus this sat im taking a class that will allow me to help the animal shelter raise them until they are ready to be released
That's great that you will be involved with the raising of WILD animals. Squirrels are precious when young but when they reach maturity they change. Research Sugar Gliders very well. They are not for everyone but are great pets if you are willing to do the extra work and make a commitment for up to 15 years. Sign on to Glider Central, you will learn everything & more about Sugar Gliders and there are lots of folks there to help you make a decision.
As an experience owner that has had both sugar gliders and southern flying squirrels at one time or another in her life... I would have to recommend the flying squirrel over the sugar glider for most people.
SFS are easier to take care of and have a more simply basic diet than that of a sugar gliders special diet... and SFS do not have scent glands that leave a strong urine smell on you and your clothing once you have handled them... sugar gliders for the most part are constantly peeing and pooping on you when you take them out of their cage for bonding time... flying squirrels when let go potty before you remove them from their cage are usually good for 30 to 60 minutes before they will need to potty again, this make bonding and play time more enjoyable.
Hope this information has help in some way or another.