I've used : Lindows, Mandrake,RedHat, and Slackware.
I am currently using Slackware and I don't think I'll ever switch( Until I finish my operating system ).Slackware is hard.. (harder) but you get more control.I used the other linuxes for about a month then I switched to Slackware 7.0, then 8.0, then 8.1, then 9.0.
And when a new one comes out I'm using that.
So really its up to you wich one you use.. I like slackware best becuase I program a lot and I find it easier to program with slack than any other operating system( Windows 3.0,3.11,95,98,XP, Dos 3.0, 3.06, 4.0, 4.5 .. included).
Oh well.... that will change... I'm gonna finish my operating system.. it is designed soley for Programming, Browsing the net, Emailing, Some graphic designing, and a little gaming.
It will still be a bit before I'm finished but.. oh well.