I have been a Stephan King fan for a long time. But I have only ever seen his films. I have not read any of his books. Beings that there are most likely many King fans of his books I figure this would be a good place to start. I have some of King's books... yeah I know, I own them but have never read them... lol 

These are the books I have. 
 
The Stand: The Complete & Uncut Edition 
Dreamcatcher 
The Dark Tower VI: Song of Susannah 
Cell 
Lisey's Story 
Under the Dome 
Desperation 
The Regulators .....picked this up at a $.99 store!, I later bought Desperation and it wasn't until I put Desperation on my bookshelf that I noticed that the spines her almost identical; It was blind luck that I got Regulators. I had no Idea that Bachman and King were one in the same :0) 

I think I may have From a Buick 8 and a couple others, but I'm not home at the moment to check. 

Anyways, of what books I do have, which would be an awesome book to read as a "First Time Stephan King Reader"? 

I do not like Stephen King books that much.  They tend to be to wordy and descriptive for me.  I like action!

But I have read a few and the one book I really enjoyed was Cell.  that was a great story.  i would start with that one.  have fun.

My vote: Stand

Don't want to add confusion by suggesting a different book, but the Stand is one of the best.  Not the best King, just the best.  It has a following, and is actually my favorite book.  I agree with Angela that Cell was fun, but a know of a lot of people that really didn't like it.  I read Under the Dome too, and the ending was weak (1000+ pages is a LOT to read for a weak ending...)  Either way, I consider the Stand to be one on the to-read-before-you-die short list anyway, so read it.  If you happen to have Salem's Lot at home, it is a great Vampire novel.

Of the list you've posted, I'd have to go with The Stand, as well.  If you're looking for a decent scare, however, I'd go with Cell. I'm in agreement with Heidi about Under the Dome having a weak ending and felt the same way about It.  Salem's Lot is still a favorite, as is The Shining (hated the movie).  If you only have book 4 of the Dark Tower series, I would strongly suggest you find the first 3 and read these in order; it does matter. 

I figured the Stand would come out on top :0)  I love the mini series, hoping the book is as good or better! I also was thinking the Dark Towers as being a Chrono series. I'll have to get a hold of the first 3, I have only hear good things about this series :0)

Cell was a pretty quick read for a Stephen King book, but of course The Stand is great.  You didn't list it, by my favorite is IT.

Read "pet sematary" It's one of King's more frightening, i think

IT for me, had a weaker ending than Under the Dome.  I was thoroughly annoyed by the ending and had Stephen King been in the vicinity, I might have bitch-slapped him.  Of course, I was 7 months pregnant and feeling particularly grumpy at the time, so it might have been a bit of an overreaction.   FWIW, Pet Sematary is the one book that King found disturbing.

You have Dreamcatcher, that is a good one.  Salem's Lot is him at his best.  But I agree with another poster, he is too wordy, jumps back and forth from present to future too much and tends to leave you twisting in the wind at the end.  I don't read him much anymore.

Leo