Good morning Sparkle,
There really isn't any debate at all! If you are comparing the two; a 2 car garage will ALWAYS beat out a single car garage when the homes are similar in location. If the area is prone to having NO garages, then obviously having one will be a step-up.
Cookie cutter in San Antonio that is MOST popular is 3/2/2! I still get soo fed up with those home builders actually still building ONE car garages that claim that it's MORE living space for your buck!! What you basically are doing is buying into that cheap excuse only to cut corners on your purchase w/out much regard to resale on the back end. Keep in mind that owning a home is owning an investment.
Here are FACTS:
Last 12 months of sales in ALL areas of SA.
1 car: 421 sales w/ average sales price of $116,324
2 car: 3229 sales w/ average sales price of $125,489 PROOF IN THE PUDDING!!
Hope that helps give you more of a clear cut answer.