As my name implies, I should be Titleist Forged only.
I've dabbled with too many other non Titleist Forged irons, all of which I have just sold and gotten rid of. If I could just have stayed loyal and faithful to Titleist Forged, I would have saved so much money.
I don't regret trying the DTC brands, or TM, or whatever, but I just end back up with a Titleist iron set anyway.
Also, I regret my Goodwood custom putter (and stamping my initials on it). I like the putter, but the shape is meh, along with the feel. Could have saved some money and put it towards a Circle T. Alas.
What else... trying some X stiff driver shafts when I clearly don't have the speed/ballstriking skills.
Too much to list!!!