High Return-on-Investment Exercises
The following are the exercises which I find give the most general physical preparedness in return for effort invested. Your mileage may vary but I've found that for the most part my experience matches the exercise science literature.
Pull-ups, chin-ups, push-ups, dips, muscle-ups, and holds, either on a bar or gymnast's rings. Weighted chins, dips, and pull-ups. "Hindu"/"judo"/dive-bomber/dand/plough push-ups. Cossack squats, burpees, back extensions, ab wheel rollouts.
Barbell exercises (done heavy through the principle of progressive overload): back squat, front squat, deadlift, Romanian deadlift, overhead press, power clean, overhead squat, power snatch, Pendlay row.
Jumping, leaping, bounding. Throwing heavy things. Tumbling.
Dumbbell cleans, snatches, swings, rows, presses, and complexes. Farmer's walks. Turkish get-ups. Lunges, weighted or unweighted.
Kettlebell swings, clean-and-presses, windmills, "flows" and complexes.
Running: 50 to 100 meter sprints, hill sprints, intervals (e.g. 1km fast; rest 30s to 1m), long slow runs from a mile to 5k. Longer runs provides diminishing returns on anything but running itself, and are quite physiologically stressful. I hear longer sprints (e.g. 400m repeats) are productive but they are still on my to-do list. Bicycling and rowing. Field sports. Jumping rope.
Circuits of body-weight exercises. Pushing a Prowler, dragging a sled, swinging a sledge or ax. Odd lifts like sandbag heaves-and-carries or tractor tire flips.
Yoga. Mobility work. Preparatory exercises for wrestling (any kind – judo, sumo, Brazilian jiujitsu, shuai jiao...) such as stance work, movement drills, and neck bridges.
You may wonder what patterns are to be found in the raw list above. I arrived here largely through application of the general and useful heuristic of doing what experts (in this case, athletes) do that matches up with your ability and goals. For someone who wants general-purpose health and fitness, this often leads to the accessory work of Olympic weightlifters and "powerbuilders" (the mostly-forgotten physical culture in the space between powerlifting and bodybuilding), some novice-level gymnastics, and running or other cardio biased towards shorter efforts.
There are many exercises that I like that did not make this list because I don't feel they improved my general fitness to a great degree, despite being fun and worth doing. Good examples are the barbell jerk, push press, kettlebell snatch, and pistol squat. I list them because I feel their failure to be productive might be my failure to work hard enough on them. There are also exercises that I simply haven't yet gotten around to trying hard to develop, but that are probably quite generally productive, such as the bench press or pull-overs.
Finally, note that probably all of these movements are in fact a skill-tree-like progression of similar movements. For example, pull-ups encompasses all the work necessary to do a single unassisted pull-up, such as jumping up and lowering yourself down or static hangs on the bar, simple variations in hand placement, as well as advanced or problem-fixing techniques like "archer" pull-ups.
— Dave Liepmann, 20 October 2019