Your budget will determine the level of insulated door you buy. One with a good (installation, labor & parts) warranty is the way to go.
The 16x 8 door i have was not an insulated one when it was installed. Last year i insulated it myself, then had a door co come out to readjust it. Since the weight increase by about 50 lbs. Based on the original quote for an insulated door. vs. Me doing it plus paying for it to be readjusted.. I saved maybe $200 - 300. However at the time i did the shop, that extra $$ was not in the budget.