I have a couple.
The Callaway Big Bertha driver, 2016 model. Added an inch to the shaft and have hit it very well.
Ping G30 irons, 4-UW. I was gaming the Taylor Made RS1 irons and was hitting them well, but had some pro shop credit built up from last season and ordered the Pings earlier in the season just to have yet another unused set of irons collecting dust in the basement.
So they come in, and I decided to take the 6-iron up to the range after I picked them up from the pro shop. Wasn't expecting to hit them all that different from the RS1's, but was amazed at just how much more forgiving they were. And how much higher the ball flew, with just a little added forgiveness. No loss in distance, more accurate dispersion rate, higher carry (which is important when you don't hit a high ball to begin with...)
Those were my two best equipment decisions this season.
Oh, and one other item. Not necessarily equipment related, but equipment no less. I bought a battery-operated Personal Golf Fan. A lithium rechargeable battery, one charge holds 6 hours of use. It fits right into the cup holder in the cart, two settings (medium and high). That bad boy came in very handy this summer, let me tell you. Of course, it was pricey too... $200. But it was worth every penny - had guys begging to ride with me for about 2 months this summer when the humidity was kicking. Great purchase!