I thought that was a joke, until halfway I realized you were serious.
What gave you the idea SDL is less professional/more stupid then DirectX??????
SDL supports everything DirectX does, such as 3D, 2D, color keying, alpha blending, sprites, networking, sound, shading, etc. You better believe SDL looks just as good as DirectX.
But really there is no contest between the two...they are about the same in the way of performance and functionality. I'm not saying don't go with DirectX...certainly DX looks very good on a resume (ok, I take that back...it does look a little better...but if you work on open source that cancels the goodness out most of the time) but don't assume that SDL isn't as good as it.
So pretty much, its a matter of opinion. Choose whatever, but my personal experience has told me SDL is better...because I've actually written something in it (I gave up on DX after I got like 200 errors for something I copied out of a book).