My number one go to is a decline bench press, it's the one exercise I really look forward to. I chose decline because it causes less strain on my rotator cuffs - an old rugby injury. If I could only ever do one exercise again, decline bench is the one. Chest, shoulders and triceps. Great burn and I love trying to hit a PB.
My least favourite exercise is deadlifts, now I do deadlifts, they are an important part of my routine - deadlifts are an excellent compound move and really useful regardless of whether you're trying to add muscle, or lose weight. However, they are just so so hard! They really challenge you, back, legs, glutes, and when you get heavy, grip strength. If I am truly pushing myself, deadlifts hit me hard, rather than 3 really full on sets, I tend to build up to a set which I know is going to hurt, but I know when it's time for set 3, I'm going to give it my all. With that said, give me a decline bench press any day over deadlifts.