What is the best workout routine?
This is a very difficult question to answer because every person is different. This is why I designed the WLC System and the WLC Workouts Manual to help you find the best style of training for you. There's going to be lots and lots of different workout routines that work for you, but finding the best should be a goal of yours.
First your workout routine should include weight lifting workouts and cardio workouts. There should always be a combination of those and the amount of cardio will go up and down depending on your goals: more cardio for fat loss goals and less for muscle building goals. Notice I said "less" for muscle building goals and not "none." Never delete cardio from your workout routine. And yes, weight lifting works your cardiovascular system, but I highly recommend medium intensity steady state cardio for cardio workouts. I like High Intensity Interval Training (HIIT) too, but only during muscle building cycles when calorie intake is much higher.
For your weight lifting routines, you should always use forms of the best overall weight lifting exercises. These exercises should ALWAYS be a part of your workout routines. These 7 exercises are the squat, deadlift, bench press, row, overhead press, chin up, and dip. There are a huge number of variations for each of those exercises BUT just those 7 movements will build an amazing body that is balanced. Since most people have some muscle groups that are strengths and some that are weaknesses, you might want to add some different exercises. For example, a leg weakness might require the addition of lunges to your workout routine. The deadlift exercise you choose to address a hamstring weakness might be the stiff legged deadlift.
The best workout routine usually doesn't include a huge number of isolation exercises like triceps extensions, bicep curls, forearm curls, rear lateral raises, side lateral raises, front raises, and more. People usually fill their workout routines with all of these isolation exercises, and they usually just add more and more recovery time and people end up making little progress. Instead, start with just the 7 base exercise movements and see what you can do. Once you are making great progress with those, you can try adding an extra exercise for a weakness you need to work on. Maybe this is standing calf raises for your calves or maybe it's side lateral raises for your side deltoids.
The main goal of the best workout routine for weight training should be to increase the amount of weight you are lifting over time. You don't have to go to failure to build muscle and strength, but sometimes you're going to need to push it a little extra. You're going to hit failure sometimes. And some workout routines that I design definitely have you going to failure but many of them do not. This all depends on your individual recovery levels. Some people can make great progress going to failure on a set of each exercise while others might have trouble recovering. Your lifestyle also greatly affects what you can handle in your workouts. For example, a very physically demanding job 6 days a week will severely limit what you can recover from in the gym. You might have to go to a low intensity, low volume, and low frequency style workout program to start making progress if you have a difficult job like that.
The foods you choose to eat, the amount and quality of sleep you get, the stress levels in your life, your relationships, current fitness levels, genetics, and more are all going to affect how much you can handle in the gym. You will get better results with the more you can do in the gym. But, be careful as some people can't do as much as others. For example, a friend of yours might be able to do very high volume workouts with lots and lots of sets to complete failure and build muscle fast. You might get zero results from doing the exact same thing. There are huge differences in people! This is why I say that the best workout routines are within the WLC Workouts Manual and used in combination with the WLC System.
You will always measure progress and know what's working the best for you when using the WLC System. This is how you find the best workout routine for you as an individual. If you have a close family member with a very similar lifestyle and he/she is making great progress with a workout routine, ask them what they are doing. Most likely, that same routine will work great for you due to the similar lifestyle and genetics.