Most efficient way to use weight machines?

[[FnG]magnolia]

Hello all. Long time lurker, first time poster looking for some guidance on a hopefully easy to answer question.

I started going to the gym about 6 weeks ago and I've been using weights machines (yes, I know) three/four times a week mixed with 20 or 30 minutes of aerobic exercise. My question is about the most efficient or 'best' way to use these machines.

So, if I'm using the bench press machine : Is 3 reps of 10 with a weight of 27kg better or worse than 3 reps of 8 with a weight of 39kg? Is it just simple arithmetic, i.e. the number of reps times the weight, with the bigger number being the 'best' option or is there more to it than this? I do the above twice in each session ( 2 lots of 3 x 10 @ 27kg or 2 lots of 3 x 8 @ 39kg) and both set ups are equally challenging. How do I know what is better for me?

I have the same question for leg presses, lat pulldowns, multipress etc.

Thanks in advance.

 

[[FnG]magnolia]

I'm aware of the benefits of free weights.

Anyone have any advice on my question?

 

[[FnG]magnolia]

Indeed, but with an AWOL OP we will never know!

Apologies.

Using the machines is nothing to do with equipment limitations and more to do with the fact that I thought machines might ease me in to doing weights. I'm aware that free weights give better and often faster results but I suppose I'm a bit nervous about going in and not having any idea what I'm doing. Having said that, the staff at the gym are really friendly and very knowledgeable so maybe I just need to bite the bullet and get on with it.

I've read all the advice and even though some of it is contradictory I've taken it all in. Thanks very much.