I haven't personally used phonegap. I have had a fried/co-worker who really likes it though. For me personally, ludei solved the problem of getting WebGL to run on the other devices and that's why I used it. I think phonegap is more well known compared to ludei (just my personal feeling) and thus may have a bigger community around it. If it's an application I would say look into phonegap if it's a game look into ludei. Or try both and see which one you prefer.