Lots of people around here like ConvertXtoDVD as an all in one commercial program. I wouldn’t call it the best possible solution, but it is simple to use and relatively fast.
Quickest time is rarely a good measure for quality.
The only time that holds true is when you use CCE or CCE Basic to convert to dvd compliant mpeg2, then use an authoring tool to put it into dvd format. CCE is a very fast encoder, and one of the best in quality, but costs $1900. CCE Basic was about $58 last time I checked. Neither are particularly simple to use.
From the sounds of it you are looking for an all in one solution instead of the encoder + authoring program route. TMPGenc Author 3 is one possibility, with higher quality than most alternatives.
For a free program, you might look at FAVC. You can use the HC encoder with it, and HC has often been compared favorably to CCE, TMPGenc and ProCoder, and is easily the best free mpeg encoder I know of.
If speed is your main criteria though, I have little help for you. Encoding times depend on the speed of your computer for the most part. And those programs that cut corners to gain speed are rarely worth using.