By order of their apparent effectiveness and my confidence in their effectiveness:
1. Magnesium - I take 450mg as citrate and 600mg as glycinate (labeled as glycinate-lysinate from Dr's Best, but I've corresponded with them and it is almost entirely glycinate)
2. Na-R-alpha-lipoic-acid - 80 or 100 mg 3x per day. Might not be necessary to use the Na-stabilised form or the pure R-form.
3. Omega-3 fish oil - stopping it and going back on at just 300mg of EPA/DHA I noticed a difference. Recently started taking about 5x that amount, and I'm not sure it is doing much more.
4. Melatonin - 6mg at bedtime, half as immediate release, half as sustained. Seemed to help with getting to sleep and staying asleep when I have gone onto it, though it's possible it has lost its effectiveness after many years.
5. Taurine - 1,000 mg at bedtime, maybe helps a little with getting to sleep and with sleep quality.
6. Panax Ginseng - This seems to lose its effectiveness if I take it for more than 3 consecutive days. So I only take occasionally at breakfast when I think a day is going to be particularly demanding - maybe 3 times a week. If I do take it 2 or 3 days in a row, I will take a break for at least as long. It seems to give me slightly more energy, improved sleep, more libido. 10 mg of ginsenosides is enough and more doesn't seem to increase the effect much.
I'm surprised people weren't talking more about magnesium (I only noticed it mentioned in terms of helping with constipation above). I do get constipation and the magnesium (especially citrate) does help with that, but my impression was that most PwCFS found magnesium helpful.
For context - I have had CFS for 12 years, I'm male, in my late 30s. My condition apparently started with a cold. For five years, it "only" cut me in half. Condition deteriorated over a few years and for the past 5 years or so I've been basically housebound and unable to work. I have tried many, many supplements (around a 100 maybe, pretty much everything people have recommended above) and many other forms of treatment - anything that seemed plausible. I have found that avoiding high glycemic loads is important. Very short sessions of high intensity interval training (HIIT) make me feel slightly better immediately, for the rest of the day and the next day. But I can only manage that on days when I'm basically not doing any other activity - no shopping, cooking, cleaning, socialising. I'm currently at 4x14 seconds, rest between sets for 24 secs, 100 secs jogging as warmup, then a couple of minutes wandering around til cooled down. The specific exercises I do are mountain climbers, jumping jacks, burpees, running on the spot while punching, all as fast as possible, each for 14 seconds. I take 1,000 IU of vitamin D a day, which is probably more important than any of the other supps, but I don't consider it a treatment for CFS. It's just that I hardly get any sun.