I don't want to burst anyone's bubbles here, but please keep in mind the difference between vintage and modern machines.
Vintage machines were often equipped with gas burners of 24,000 BTU/h or more (gas), and 4,500W heating elements (electric), because back then the controllers were just a timer and thermostats. Finishing as fast as possible was the goal, particularly with spin speeds on the low side for most washers.
Modern dryers often have 5,200W heating elements and gas burners of 22,000 BTH/h or less (some are being equipped with 16,000 BTU/h burners). Mostly, now that the controllers include a moisture sensor, both dryers use the same controller and the gas burners are tuned to work well with the moisture sensor, so it's about as fast to use an electric or gas dryer.
People who live in areas with hydroelectric power plants may find that electric dryers can be more economical than gas. People with thermoelectric power plants will probably pay less for gas.
The other consideration is that electric dryers provide a neutral atmosphere -- the air is just warmed up. Gas dryers provide a reducing atmosphere, because oxygen is removed from the air to burn the gas, and the combustion by-products are then circulated inside the drum. Most people don't find any problem with that, but some fabrics do not do well with reducing atmosphere and won't last as long as possible, because most fabrics are in fact more resistant to oxidizers (like chlorine bleach, perborates and percarbonates) which are routinely used for laundry.
I must say that most of the above is only important to us, who like to talk about details -- in practice most people don't notice any difference between gas and electric dryers and, if they do, it has more to do with cost per load than anything else. And even there, the cost per load will vary with the price of utilities.