There are many routines, but again in truth, the magic/gains will be in your consistency, effort and dedication to just getting or making yourself better.
IMO, pick a known one and stick to it for a good while.
4 days per week is plenty of days per, to get to nearly 95% of your potential. Even 3 days is plenty.
Here are the points that will make the difference and the points that are most likely in every top program, from Starting Strength to 5x5's to 531 to, (should I go on?)
Use the big *5-7 compound exercises first and fore most
Be consistent with making the workouts every week
Add weight to the bar when you can
Eat enough and or the better foods/fresh is best
Rest and recover
Repeat
*Compounds of note...
Squats
Deadlifts
Leg Pressing
Rowing/chinning
OH Pressing (preferably standing perhaps)
Bench or Incline Pressing and or dips
Some abs or core stability work
The biggest concentration on these movements, done consistently with multi sets and reps (for the most part) will produce big systemic changes in body mass and strength.
Afterwards any smaller muscle or iso work ie. limbs etc. etc. will work.
Try not to get caught up in the little stuff but just concentrate on the first top points.
