4K or UltraHD upload

Should I go with 4096x2160 or 3840x2160 resolution upload on Pond5?

Go with 4096x2304 - from this format everyone can make the 3840x2160 Ultra HD if needed.

I checked Wikipedia and the number 2304, at list on this page, is just not there:
http://en.wikipedia.org/wiki/4K_(resolution)
Of course the wiki results are meaningless. I upload just like Zygis said, 4096x2304, because from there the buyer can crop, pan and zoom anything s/he wants.

What about same size as original photos like 4000X3000 ??
Any idea?

there are cases where having the larger size might not work, as an example, SONY Vegas not too long ago only supported videos of 1920x1080 and not any larger, so I could not use it to edit or render side-by-side 3d which is 3840x1080.

remember that you are selling your videos for the consumer, so what is important is not what your favorite video editing software is (I used an older version of vegas), but what your buyer uses. there are 3 or 4 major editing programs and you should probably check to make sure they are all compatible with your output.

as an example, anyone who uses a PC has to install quicktime to add .mov support, it isn't included with any software that I know of.

I had to test around 10 different video editing programs to try and find one that support side-by-side full HD and never found one that supported it for importing AND rendering.

Mr. T wrote: "remember that you are selling your videos for the consumer,"

I wonder if housewife/Opa/Oma will come and shop in Pond5 !

Well I was thinking I am selling to producers/production house etc, so B to B ?
Well I am not expert, and you seems are the big player here, so we have to believe you!! Should we all reduce our price of Footage to suit your "consumer" ? :D

4096x2160 or 3840x2160 the main difference is the aspect ratio, 3840 is the same size format to 1920 without cropping 4096 is a cinema size and would need trimming for HD.

I would consider UHD vs 4K. As Normstock said the aspect ratio of UHD is 16:9 which is what is probably going to be most popular. Having said that, there is no reason not to submit both resolutions and that way the customer has a choice.

I'm going to start creating UHD clips this year and most likely will not work in true 4K.

I believe UHD will become more popular due to it's 16:9 proportion that is the same for HD. I don't think buyers would opt any more for the DCI 4K versus the UHD 4K. The other agency that automatically downsizes 4K to HD makes the HD a non-standard size keeping it's proportion the same as DCI 4K. I believe that will scare buyers away, they want 1920x1080 HD. If you shoot DCI 4K make sure you leave room to allow buyers to crop it to 16:9 without losing something important.