Been a gym rat since I was 17. 51 now. It has been worth it, you guns stay with it and it will mean when you're middle age you will still feel great and look better.
Only supplementation I do anymore is protein bar with (not instead) breakfast and lunch and a major brand "men over 50" multi-vitamin multi-mineral tablet about every other day, as daily proved to be too much for me.
Among bars there are fewer and fewer labelers than haven't sold out and jumped on the cheapo soy protein band wagon. As you know, soy protein and most soy products (lecithin is in almost everything) upset the endocrine balance. I've cut as much soy out of my diet as practical, and the only easily available bar I can find that still relies on whey and contains no soy protein (but does have lecithin) is Pure Protein by Worldwide Sport Nutrition Supplements. To the OP, WSNS also is a registered supporter of the National MS Society. A big thing with protein supplements is label claims on the package. Bill Phillips back in the day when he ran EAS (I think?) did a book called the sports supplement review or something and in it they had a lot of products tested for actual protein content vs what the label claimed and a lot of products did not stack up. So that's always a concern, if you're getting what you're paying for protein wise. Pure Protein bars claim 20g per bar, no idea if its true.
I used to use creatine back in the day, were supposed to cycle 12 weeks on and 12 off to keep your creatine receptors frosty or something. Is that still done?
If you're upper 40's or over 50 DHEA might be a consideration if you're low on it, which can happen when you get older. Building block for testosterone. But the only effective way to get it is cream form and transdermal absorption. The gastro tract and liver can disrupt the effectiveness if taken orally due to how its metabolized or something. I was up on it a while back but forgot most of it. However, you should first get tested to see if you are even low on it because while it declines with the onset of middle age it may not drop below the threshold where it would be beneficial to supplement it and you don't want too much.