Magnesium threonate is considered to be the best form by most experts with an opinion, but it is also the most expensive.

If you're not poor, consider buying a jar of that because it gets you started with the least cognitive overhead, then if you respond positively to that, consider switching to something cheaper:

https://nootropicsdepot.com/magnesium-l-threonate-powder/

Chlorophyll's great if you can consume it in adequate quantities. Usually brings other beneficial nutrients as a side effect.

Easier to just start drinking mineral water.

I make my own San Pellegrino clone with RO water which has a fair bit of magnesium in it and it is far more pleasant way to get it than a supplement.

my understanding is that bisglycinate is effective without causing the intestinal distress that other forms can cause

I'm probably unusually sensitive, but I hate having to take glycine every time I want to take magnesium. The glycine causes mild symptoms sometimes and tastes aversive.

Most people are not affected in any way by glycine. A normal daily intake of proteins is likely to contain at least 2 to 3 grams of glycine, which is several times more than you can get from a magnesium bisglycinate supplement.

Magnesium citrate is insoluble in water, so it does not have any strong taste. It should be dissolved in the acid environment of the stomach, but it can precipitate again in the intestine, avoiding absorption. Moreover, it can have laxative effects.

The advantage of magnesium bisglycinate (which is the same for the bisglycinates of iron, zinc, manganese or copper) is that it is soluble in water and that it remains soluble until it is absorbed.

The aversive taste that you do not like is probably not that of glycine, but of the magnesium itself. The magnesium ions are bitter (hence the name "bitter salt" for magnesium sulfate). With an insoluble form of magnesium, like citrate, you feel much less the taste of magnesium (but then that has worse behavior in the intestine).

If you do not want to taste the magnesium, you can swallow capsules. Nevertheless, I prefer to drink water in which I have dissolved pure magnesium bisglycinate powder (and also pure potassium citrate powder). After that, fresh water tastes sweet :-)

>aversive taste that you do not like is probably not that of glycine

No, the aversive taste is exactly the aversive taste of glycine in free form. Glycine seems to trigger the mast cells, and my mast cells are chronically hypersensitive, which is why I preface my initial comment with, "I'm probably unusually sensitive".

(I prefer powders to pills, especially for something I take as much of as I take magnesium.)

>A normal daily intake of proteins is likely to contain at least 2 to 3 grams of glycine

There can be big differences in effect between eating a lot of protein and taking a single AA -- especially on an empty stomach.