It depends on the friend. I've had online friends be better than my IRL friends sometimes. Talk to me on the phone when I had no computer, etc. Also, occasionally with my online friends, if we have something the other person needs, we'll mail it, usually just for shipping cost or sometimes free. Like my friend needed a battery charger, I had a spare, so I mailed it to him. This friend, I talk to almost everyday, and I've known him since 2005. However, now I have very few online friends, I only have about 5 I talk to on any consistent basis. It's one of those things where, 200 people on the buddylist, but only 15ish you talk to regularly, now it's dropped to 5 or less.
Online friends are like IRL friends, you have real friends like I've described, where you might as well just be best IRL friends, then people you just talk to about stupid stuff occasionally, then people who ignore you/dislike you but are too passive aggressive to actually tell you. But yeah, in my case, a few of my internet friends have been as real or moreso real friends than my "real" friends.
Now, it's weird, though, as I've realized my social problems apply to online, too, so now I don't seek out online friendship as much anymore. My problem in both of them is, I'm quite outgoing, but still a social idiot, so my outgoingness actually makes things worse than if I was quiet and shy, works the same online, I had one online friend block me, I saw him on a different screen name, was like "hey, why'd you block me?" and he said I talked too much about myself. So yeah...