Both companies make a great product, however I feel Titleist has a wider range of irons from MB's - AP1's. I have seen juniors play pure blades as well as GI irons. I would definitely see a fitter and they will dial you into the correct head & shaft for your game. I'm bias towards Titleist, I believe the AP2's are the best iron in the game.

Echoing the earlier replies, both offer very good products and you owe it to yourself to pursue a proper fitting. After playing png i-series irons for a decade, I switched to the AP2. What I experienced was a club that provided better feedback of the ball strike and the result of improved consistency in my game. Others opinions may surely vary, but I've been more than satisfied with the switch. Good luck with your search.