In keeping with my post on the "worst buy" thread...
My #1 best buy ever is... my second wife! :lol:
On a musical front, I can't decide - they're all really good and it depends what mood I'm in - but it might have to be my old Laney Pro-Tube 50W m/v combo. It wasn't quite what we were expecting when we ordered it in 1982 (1x12, not 2x12), but it did hundreds of gigs. I bought several other amps over the years but always came back to this one.
I haven't used it for years now, but if I ever had to play live again, I'd want to get it overhauled and drag it out again (I'd need someone to carry it though :lol:)