U of Phoenix is pretty much the most popular and well-known of the online universities. With that said, it's going to probably be the most developed in that it will be the most user-friendly in its interface, be the most professional in its feel, and have the most pictures of multicultural smiling faces. So it's probably where you want to start your information-gathering. Not becuase it should be the standard education-wise, but it will give you the best feel for what you might want from other online universties and such.
Clearly it's better to get a degree from an actual school (if, in a hypothetical situation, one could do either-or). I won't go into the full reasons for that, but some of them are that it's easier to cheat through an online program, you won't get the experience of dealing with people IRL like you would going to a regular classroom, and so on. With that said, some people can only go to Uni online, and in this cause it's surely better than not getting a degree at all. If you or your family is in a tight spot and this is what would work best for you, then by all means go for it!