Great thread topic jeff! Do I have to limit to just three?
1983 GMC K2500 6.2 diesel 4x4 - Was my first vehicle, my dads' former daily driver and plow rig and generally abused in every way possible. Never reliable, but one of the coolest trucks IMO. Still have it in a field. Someday, a driver resto with Cummins swap.
2004 GMC Sierra 1500 4x4 - Was my daily driver, plow truck, tow rig and all around reliable good truck that punched way above its weight.
2003 Ford F450 2wd - My dump truck that I talk about incessantly here on TBN. I love this freaking truck. 6 speed with the last of the 7.3PS. It's fun to drive, and gets work done. It's never let me down, but I've spent some money on it. Well worth it in my opinion. They will have to pry this truck from my cold dead fingers.
Honorable mentions:
1997 F150 4x4 - RCSB with 5 speed stick and V6. Light and fast! Nearly lost my license in this truck. 3rd gear could roll at 20mph all the way to 90mph. If it had the V8, I'd have kept it forever. Bad engine issues though.
2001 F150 4x4 - RCSB with auto and V6. First new vehicle. Reliable daily driver. Would have been great with the 5 speed. I really like the jellybean F150s. Appearance took some time to get used to, but the size was perfect. Big enough to be comfortable and work, small enough to park and drive in the city. Great visibility and very comfortable.
1976 Blazer 4x4 - I was given this truck by a guy that wanted it out of his yard. After sitting for years, I changed the oil, put a battery and gas in it and pulled the spark plugs to juice up the cylinders with some MMO. Fired up and drove it home. That was a fun offroader and had quite a few memorable adventures with buddies with that rig. I gave it away and regret it now, but had no place to keep it. Had to go.
2012 Chevy 2500 -Second new vehicle. Was a great towing rig, reliable as a stone. Too big and thirsty for a daily driver, and too nice to work hard. So it sat around most of the time. Sold last year, and surprisingly I don't really miss it. Maybe that will change.