According to Joe Weiders “Ultimate Bodybuilding”, these are the most
common upper body (except arms) exercises among top bodybuilders…

For the back…
Seated cable row 32/42
Front chin (pull-up) 20/42
Pulldown behind neck 17/42
Barbell row 16/42
Front pulldown 15/42
Narrow grip pulldown/-chin 11/42
Chin behind neck 9/42

For the chest…
Dumbbell flye 26/30
Bench press 21/30
Incline bench press 18/30
Cable crossover 16/20
Parallel bar dip 15/30
[Cross bench] pullover 15/30
Dumbbell press 14/30

For the shoulders…
Press behind neck 18/27
Dumbbell side lateral 16/27
Upright row 10/27
Cable side lateral 8/27 (one hand)
Dumbbell press 7/27

For the abs…
Roman chair sit-up 13/18
Bench/Incline leg raise 11/18
Crunch 10/18
Hanging leg raise 9/18
Incline sit-up 8/18
Cable crunch 7/18

So, are these the best exercises? Well, that depends on what you want.
Do you want mass or definition? Do you want width on thickness? Do you
want overall mass? Do you want lowe abs? Do you want upper chest? Are
you on a mass cycle or pre-contest?

Here0…7s my list…

Overall mass: Deadlift
Back width (upper lats): Front pull-up (weighted)
Back mass/thickness: Barbell row
Lower lats: Chin (narrow grip) (weighted)
Lat isolation: Stiff arm pulldown
Lower back: Back extension
Overall chest: Bench press
Upper chest: Incline press
Lower chest: Dip (weighted)
Shoulder mass: Press behind neck
Side delts: Dumbbell side lateral
Lower abs: Reverse (incline) crunch
Overall abs: Crunch (weighted)

For the back, you should do one exercise for lats ie. width, one for
thickness and mass and one for lower back. Thus, front pullup, barbell
row and back extension. If you only do one exercise, I would choose
chin or narrow grip pulldown, altough barbell row and seated row are
good as well. Perhaps you should alternate these.

Pretty much all bodybuilders do barbell rows, and chins/pull-ups are
common too. Yates favors a narrow grip (on barbell rows and chins) and
many others (Haney, Arnold, Coleman) seem to lean towards wide grip
(pull-ups). You should do pulldowns as well, if you can0…7t do too many
reps on the chinning bar.

For the chest, the most common exercises are bench press and incline
press. Some people opt to use dumbbells in these moves, if they get a
better feel that way. Crossovers are pretty much a pre-contest
isolation exercise. If you do one exercise, you0…7ll probably do just
fine with regular benching.

For the shoulders it is advisable to do one mass exercise and one
width exercise for the side delts. Thus, press behind neck and
dumbbell lateral. Again, some people get a better feel with dumbbell
presses. Cable side lateral is mainly a pre-contest isolation
exercise.

The single best exercise for abs is (weighted) crunch. If you need
lower abs, a good isolation exercise is reverse crunch. Hanging knee
raise is good as well, put it involves the illiopsoas (hip flexors) to
a greater degree.

These are pretty much the basic exercises that most top bodybuilders
use most of the time. Mostly, their routines are remarkably similar.
The most useful machines are probably leverage maschines (Hammer etc.)
and pullover (Nautilus etc.)