Like everyone else, i am no expert but here are my experiences. I have three smaller ponds - each with magnetic drive pumps. One is 500 gph, another 700 gph, and one 2000 gph plus rating. Magnetic drive pumps are generally quieter and use less electricity. Mine last a long time. Every one of them needs a degree of service though. They all require filters on the inlet side of some sort and these need to be cleaned of debris on a regular basis. They do make backwashable pre-filters which is something else you can check out. You will be thankful to not have to clean off the pump screen every couple of days - trust me.
As for flow, you are going to want to be at least 2000 gph or more to have any kind of flow like you see in the picture you attached. Let's take a 3600 gph pump as an example. This is flowing 60 gallons per minute. This is .1337 cubic feet per second. Or about a half-inch deep stream over four feet wide. (I think) Now if you narrow the stream it will get deeper and faster, then widen out and slow down into a pool, then narrow again - all that would make it look interesting too.
Remember that as you go up in elevation from the pump, the capacity will drop. The ratings should be easily found on any pump schematic.
Lastly - welcome to PondBoss. There are great people here. I don't get much time to post and read as I want but try to share my experiences whenever I can to pay forward the friendship and expertise I have found here.
