I'd say this is the best place for inexperienced users, followed closely by ubuntuforums. The others are more advanced.
Askubuntu is good because answers are voted on and users are ranked. Ubuntuforums is also very good but there's no vetting. There is a lot of good advice and also a lot of bad advice. And how are noobs supposed to tell the difference?
You can't really tell if a forum users is reliable from their number of posts. I've seen people with well over 1000 posts that don't really particularly know what they're talking about. And others with 10 who were clearly pretty expert.
Biggest hint IMO: whatever it is ask your question clearly. Learn how to display your hardware devices' make/model. Saying it's some model with a 1.9GHz cpu doesn't help much.
It also helps a lot if you can say what you were doing when you had problems. This isn't easy sometimes. You may have to learn how to find log files.
This is just like getting anything fixed. If you can explain what's wrong in understandable language it's going to be easier to fix.