My answers would be any basic protein powder simply for convenience sake if it helps you hit your daily protein needs more easily... creatine monohydrate since it's the most research backed muscle building compound there is and is very inexpensive... and vitamin D3 since most people are not in the optimal range as is.

Fish oil and creatine, because they are so efficacious and so well-researched for both body and brain performance. The former, of course, only if not rancid and from a quality source. The third would likely be cannabidiol (CBD), the legal, non-psychoactive form of THC for sleep and relaxation.

Proven for performance: creatine, citrulline malate, caffeine, protein when I need it.

Some promising early research, but not enough to say they work conclusively (and they're cheap, so just taking a better safe than sorry approach): taurine, TMG (betaine anhydrous), spirullina.

General health (better safe than sorry when I'm not getting much variety in my diet)
athlete vitamin from Citadel Nutrition (magnesium, zinc, K2, D3), garlic, and vitamin A.

Currently I'm taking caffeine pills (300 mg pre-workout 10 min before I workout), Whey protein powder (amount varies based on how much protein I get from actual food),10 mg melatonin to help me sleep (taken 30 min before bed).

Here are 3 supplements I often recommend.

1. Caffeine. Not because it's that effective to enhance your performance, as it's not, at least not in sustainable dosages, but simply because it makes your workouts more enjoyable.

2. Creatine monohydrate. It doesn't work for everyone (I'm a non-responder myself), but for those that benefit from it, it's still the most effective supplement for strength trainees on the market and it's cheap to boot.

3. Vitamin D3. Unless you're regularly exposed to a significant amount of sunlight, there's simply no other way to ensure optimal vitamin D levels and the benefits of this are innumerable.

These are the three supplements that I cannot do without.

1) Beta Alanine (6 grams pre-workout on training days; first thing when I wake up on non-training days)

2) Citrulline Malate (8 grams pre workout)

3) Creatine (5 grams daily)

Here are four supplements I regularly use. I don't automatically recommend them to everyone else. I'd only consider recommending them to someone else if they were in a similar situation to me.

1. Algae based omega-3
I like to get a direct source of DHA/EPA in supplemental form since the only source I get in my diet is ALA from flax, hemp, walnuts, canola, and chia. And I prefer algae to fish as it better aligns with my environmental and animal welfare values.

2. Vitamin K2
I don't eat food sources with K2, and at this point I'm not sure how much my body is producing. So I take a low dose K2 supplement to be safe.

3. Vitamin D3
I live in Boston. And work indoors. So my vitamin D tends to run borderline low. I use a supplement for 9 months out of the year (I volunteer at a farm outside in the summer so I tend to do ok during those months without a supplement). I get tested annually to make sure I'm not running too high or too low.

4. Zinc
About four days per week I like to use a zinc supplement. I find that my immune system does a bit better. And I don't always get enough in my diet.

I’ll give you my 3:

1) Fish Oil

2) Magnesium
3) Glucosamine

My three most-recommended supplements that I take pretty much every single day are as follows:

1. “Greens” supplement. The brand I take is Athletic Greens. It’s essentially a powdered “real food” multivitamin. This is nutritional insurance for when the food I’m eating doesn’t completely cover all the nutrients I need. This is a supplement that I HIGHLY recommend and it’s one that I never go without.

2. Micellar Casein/Whey protein blend. This is what I use to increase my protein intake, especially post-workout. The blend of these two proteins is highly anabolic.

3. Mineral Combo...Magnesium, Zinc and Iodine. I find these to be the three biggest impact minerals to take. Most people are deficient in all three of these. They’re tough to get enough of in food and they’re critical for anybody training hard.

Protein, creatine, and a greens supplement. Creatine has been tested and proven more than any other supplement. Protein is simply something we need more of if we're training.

And a greens supplement just helps me get nutrients I'm lacking.