My first vote would be: Hogan Apex 1999 and second: Mizuno MP29.
best blades of all time - Page 3
Any Titleist muscleback. Currently have 710-MB. I also have a set of Mizuno MP-69's but they lack the comforting "thwack" sound (after impact) that I have always enjoyed in a Titleist. In the hands the mizzies and the titleist feel the same but the impact sound seems slightly different. I guess you never forget your first love---for me it was a set of Titleist Tour Model blades that I used as a junior golfer in the late 80's. Looking forward to picking up some Miura's or Scratch SB-1's someday. Perhaps those will lead to the holy grail of blade perfection. But something tells me that a perfectly solid shot with a Titleist blade, a certain auditory quality, is what I will always associate with ball striking bliss. In spite of Miura San's sweaty, painstaking toil at his forge.
Gauge Design by far the best blades I have when I am traveling overseas (I have a set stored in Asia so I don't have to lug a club around when I am traveling for business ).
I also have Mizuno MP-68 that I use in the States and while Mizuno MP-68's are great, Gauge blades feel superior and looks cleaner.
not sure if going Retro is upgrading however unless you mean going to a forged blade from a GI cast cavity back, which is what I did. The Hogan Edge as most know is a perimeter weighted forged cavity back. I used to play DCI Blacks which were a nice set of irons but not that easy to hit.
I am prejudiced, but I would say you can't go wrong with any of the Hogan's. The APEX Plus has some good reviews. One set is a combo in that the longer irons are muscle backed and the mid to short irons are cavity back, but all are forged. Prices anywhere from $125 and up with an occasional set under $100. Some I have seen were outfitted with Rifle Shafts. The ones I have are APEX 3. You can also find individual clubs $12 and up. Might be a good idea to just get a 7 iron and see how you like it.