Over the years I've found that hybrids, fairway woods, after-market wedges, and irons really haven't changed that much with regard to performance (for me). Not to say that I don't have a set of irons that I prefer over a few other backup sets in the garage... but that I've really not seen an enormous difference in performance either way.
I'm a PING iron fan and honestly I don't think I play the G model irons any better than the G30 model irons from a few years prior. Forgiving, larger face, larger hitting area, bigger sweet spot, higher launching, which some of us need as we get into our older years and can't physically muster the swing speed like we used to, to get the ball airborne a little quicker.
My two favorite clubs in my bag are my driver (2015 Callaway Big Bertha) and my Ping CRAZ-E iWi mallet putter (which has to be at least 10 years old).
The putter has been in the bag the longest... at least 6-7 years. I used to be a blade putter guy, but always putted with the toe up. Then I started experimenting with mallets back about 8 years ago, which are a tad heavier, and came across the iWi which I immediately fell in love with. I inserted the heaviest perimeter weights on the heel and toe (preferring the heavier feel), and then figured out that by cutting the putter shaft down a few inches - the putter would be closer to my body at setup and the sole was more flat to the ground. This also got my eyes more over the ball at address, while also helping keep my hands closer to my legs, my elbows closer to my sides (versus extending outward). I hunch over the ball when I'm putting, and never wanted to change that. Nickalus was a "huncher" and did alright, so I figured if it was good enough for Jack - why change?
My driver and my putting are (generally) the strongest aspects of my game. I've never been a horrible iron player, so I feel like I could figure out how to make just about any game improvement iron work, since most of them are based on the same forgiveness formulas. Those who play blades or more demanding irons with less forgiveness - I'm sure there's a lot more variance between feel and performance that is required and there could perhaps be a much larger difference. But in game improvement irons - not so much.
For me it's my driver and my putter. Although I'm always in the market for a longer tee ball, the putter is pretty much off-limits. Not saying that I've found the Holy Grail in putters, but this one will most likely stay in my bag as long as I keep playing. When you discover that confidence and then develop a history of good memories and confidence with a club - it's hard to replace it.