The Shield is going to be thinner and a little lighter weight than just about everything else referenced in this thread and for me that matters, for others it might not matter much. I believe Shield weighs in at 19oz. Prior to buying the Shield 9 in March or April when they first hit the shelves, my usual carry gun was the CS9. Again, I liked the size/weight/concealablity. The Shield is just a little smaller in all dimensions. I'm sold on S&W quality and dependability....for EDC it's the brand that gets my vote, but I do own Ruger, Bersa and Glocks too. I have heard lots of negative comments about both KelTec and Ruger LCP triggers but have not personally shot either.
I'm waiting on delivery of a Shield40. As someone else pointed out in this thread, if you buy the Shield 40 you can convert to 9 with a simple $75 barrel purchase...a very compelling argument for getting the 40 available to you for what seems to be a fair price. I'd be tempted to go that route. The M&P 9C is another good choice, especially given that you like the M&P FS. I have 2 M&P's but again the Shield is gonna be a tad smaller/thinner than the 9C. So many choices for one to ponder.....good luck.