I recently purchased a set of irons myself and I am also about a 12 handicap. My advice to you would be to go to a golf store or a Dick's sporting goods and hit as many different irons as you can. Before I went in I had made up my mind that I was not going to have any preconceived ideas of what I wanted. This way I just kept hitting clubs and narrowing my list as I went along. After a couple of trips to the store and about 3 hours of hitting I had it narrowed down to two sets.
Like you, I had previously played "players" irons and not the cavity back game improvement irons. But after all that testing the two sets I liked the best and had the most success with were the Cleveland CG Golds and the King Cobra FP.
I know, I know how could you possibly go from muscle backs to game improvement irons? Well, I wish I had done it a long time ago. I am playing the best I have ever played with my irons and it just took getting my macho mindset out of the way and actually playing what works best for me.
"The future ain't what it used to be."