Weight Machines

The barbell, the dumbbells, the bench, the squat rack, the pullup bar and the dip station. Generally speaking anything else is a waste of time. Working with free weights and bodyweight exercises will produce far better results (and assuming your form is good, leave you a lot less likely to injure yourself) than machines.

They are not a waste of time (that would be sitting on your *kitten* watching the TV...) but they are not as effective as free weights.

To actually answer your question - the machines that allow you to do compound lifts would be "better" than machines that only allow you to do isolation exercises.
To take it slightly further a cable machine may well be more effective than a machine that restricts you to a prescribed range of movement.

Personally I use a mixture of barbell, dumbbell, cable, bodyweight and even the much derided weight machines as I like variety and my two gyms aren't blessed with a lot of equipment so I have to be flexible in my training methods.

Usually at a gym there is someone there on staff who will give you a basic orientation on how to use the equipment and which part of the body they help. At the machines at our gym, there is a plaque on each machine which tells how to use it and a picture of a person with muscle groups highlighted so you know what muscles you're working.

For strengthening, I prefer to use free weights.

Well, I also use free weights and take group classes that incorporate free weights. Also, have used the cord weight area. Unfortunately I don't use the squat rack or barbell every often because it is always the "grunt section" which I know is not the greatest excuse in the world... I have been lifting 12 lbs. dumbbells. I may increase to 15 lbs. but man that seems like a huge jump..

You should really look into doing an actual program. My wife really liked New Rules of Lifting for Women and I have recently purchased New Rules of Lifting Supercharged...I initially bought it for more knowledge...I like knowledge...it has been a phenomenal read and I'm going to work the programs in the book.

They are different than what I've been doing in that I've been primarily focused on strength and "heavy" lifting...this program takes me through various cycles that focus on different things...metabolic conditioning with weighted circuits, hypertrophy, and strength, power, etc. It also provides for plenty of variation of the all essential compound movements (squat, dead lift, and presses) that are used at various points within the cycles...i.e. goblet squats and overhead squats are not optimal for "strength" work...but they're great in a circuit training, higher rep-lower weight cycle...front squats with some romanian dead lifts during a hypertrophy sequence and heavy back squats during a strength sequence.

Perhaps saying machines are a waste of time is a bit overboard...but really, they shouldn't be the foundation of your routine...they should supplement and assist with the other compound work you are doing. I'm partial to cable machines if I'm going to use a machine for assistance work though as at least they allow for a more natural range of motion...a machine does not. A machine also teaches you absolutely nothing about form so I wouldn't count on them for that.

The point of all of this is just to say that you should do an actual routine...you aren't going to get the results you want just willy nilly going in and pushing and pulling weight, whether that is with free weights or a machine...you need proper programming to get the results that most people are looking for when they weight train.

I highly recommend New Rules Supercharged or NROLFW...even if you don't do the programs, they are excellent reads...Supercharged in particular really goes into a lot of detail as to why you would want to do X rather than Y and will teach you a lot about the basics of lifting...why you should lift...and how you should lift.