Yes it has been asked a lot, and remember at one point you may have been the one that asked that question. So please be patient and provide a link or answer the question, if you cannot do one or the other please don't bother to post a vauge answer.
If you are looking for information on which Linux might work for you, I think one of the best places to start is www.distrowatch.com
you will find a ranking of the most popular at the moment a short discription of each one and review links as well as other links for each one. I know a bit wordy but you get the idea.
My personal opinon, If you want to learn Linux then Slackware is excellent. I was supprised how simple many things were. But and thats a big BUT, I had to commit to a little reading and be willing to configure most of the system with a text editor. But I must say its not perfect nor is any Linux perfect. I have found now that I have dug into Slackware and am comfortable with it I cannot get comfortable with any other. I control what is running, I know the system inside and out now, setting up IPtables, Burner, Mouse, Video, etc. Compiling software is interesting and takes a little time. But once you have your slackware system set up its fast and its a good feeling to know you learned a lot.
So slackware is not for everyone, it takes a little effort and commitment.
As far as Redhat and Mandrake hmmm I have found them to be slow and well buggy, that could be my computers who knows but slackware is rock solid on my equipment.
Give Lycoris a try, no it does not have the latest shell but it is very nice to work with and comes ready to rock.