The short answer is find a professional fitter and let them guide you.

That person will see how you hit your current irons and may want you to consider T100/T200 as well as 620 CB. As well as find a shaft for the best combo for your game.

My suggestion would go to a Titleist Club Fitting for the best results.

Find a shop with a Titleist fitting cart and test all the different shaft options. Titleist does offer some different shafts at no upcharge. Making an investment in a new set of irons I would want to test as many shafts as I could. Personally I'm a 6.9 handicap and play the T100 irons, seem to have struck a great balance between players MB irons & game improvement irons. Just from looks alone my preference is the simple, clean look of the 620 MB, however my game is a T100 at best.

I have the project X LZ in my 718 AP2 that I was fitted for at my local box store that I now know the fitting wasn’t done very well. I lost about 7-10 yards coming from TM MC irons. I would suggest doing a Titleist fitting outdoor so you can actually see the ball flight.

I still like the irons but wish I had been fitted by a Titleist rep. Which I will do the summer after the next iron release. I joined a year and a half after getting my ap2 or else I would have taken the advice of all the people here and done a proper fitting.