"Which is better" is really not a very good question to ask--"which to use" is more appropriate, the answer depending on a number of things, including:
1) Where you live. If you live in PAL land, your recorded footage will be 50 or 25 fps--NTSC land, 30 or 60 fps. Although changing frame rate (PAL to NTSC or NTSC to PAL) can be done, it is NOT recommended and should be avoided. You can, however, change from 50 fps to 25 fps or 60 fps to 30 fps without issue.
2) Motion content. If you have high motion content, a higher frame rate will reduce "judder", especially during pans. If your frame rate is 24, 25 or even 30 fps, it is very easy for the eye to detect individual frames during pans. The result is very jerky or juddery motion which some (including me) find very annoying. On the other hand, if nothing much is moving very quickly, a lower frame rate may result in a higher quality recording in that more bits per frame will be used.
3)Delivery. If your goal is to upload to YouTube, there is another trade-off. Higher frame rates (60 fps) may produce smoother video for action videos, but many viewers will not have sufficient internet download speed to ensure smooth playback. Even with a pretty fast download speed (100 Mbps), I still have dropped frames when viewing 60 fps videos.
Bottom line--it's a trade-off. What I would suggest is to simply try different frame rates and find which works best for you.
As Wayne pointed out, if you are in North America or Japan your TV standard is NTSC 30/60 fps. If you are in Europe, Australia, or other pars of the world, your TV standard is PAL 25/50fps. (If you are in France it's SECAM but we won't go there...) You should use the format appropriate for your camera and country format.
To answer your question directly, I doubt that the human eye can detect any different over about 48fps. 50 and 60 were choosen because they are double the 25 PAL and 30 NTSC standards.