The standard survey parameters for our own drones are as follow: 100m altitude, 15 m/s speed, survey pattern conducive to 80% image sidelap.
When choosing a survey drone, efficiency should be your biggest concern. Agribotix has found 15m/s to be a good survey speed that gets the job done quickly without blurring the images. We do not recommend going any faster than this. With this in mind as your max speed, you should pick a drone with the greatest flight time, so that you can survey the maximum area in a single flight.
There are dozens of drones on the market, many of them specifically designed for surveys. Consider your specific needs, such as the acreage of the areas you plan to survey and your price point.
Another thing to consider is the choice of cameras.