The best form of B12 is not known. What is in fashion is different in different countries. Supply, what has been used before, difficulty storing, profit, etc. It is also the newest and that is often seen as better.
Hydroxocobalamin is often touted as the best. The only justification is that blood tests show it releases better in the body.
Cyanocobalamin is seen as 'bad". Perhaps as it has been shown that oral Cyanocobalamin is not as effective as injections in general.
Methylcobalamin is touted as being more bioactive and what is in the body naturally.
Adenosylcobalamin is the forgotten one as it is not available to inject.
I go with the only way to discover "what works for me" is to do a trial. I have no idea what someone is experiencing when they write what works for me. It is not knowable. Good enough does not interest me.
I experienced lifelong B12 deficiency so there is no measure compared to before.
So I have done many trials and four major ones. I have experienced improvement with each one including only oral Cynocabalamin and only sublingual.
I did not experience much improvement with injecting Methylcobalamin I did with injecting Methylcobalamin and SL Adenosylcobalamin.
I accept that some people experience improvement for years, up to 8. I do not except this has to be the only way just because no one has tried any thing different. My choice.
I am leaning towards seeing supplementation as nutrition/eating. I do not have to nor can be perfect I only need to come close enough so my body can adjust.
I am thinking of two things in my future. One is to increase injections to 4 a day and the other is to inject the three forms available and to take Adenosylcobalamin SL.
I do not expect any medical personal to bless my methods nor accept my results unless they are negative.
Feel free to point out any flaws in my evaluation. I would really appreciate that.