I used SAMe by NatureMade for over 10 yrs. I took it mostly for my bad knee, and it worked, and allowed me to avoid a knee replacement.

I stopped it thinking I was home free, but alas my arthritis is progressive. It really helped me thru the menopause too and in my job where stress was STRESS!!!!!!

I used only 200mg Generic from RiteAid for a short time, and it seemed to work when added to the 400mg NatureMade to give me 600mg a day.

I bought and still buy occasionally mine at Costco. The prices now are easily 1/2 less than in the past. I believe 60 400mg NatureMade are about $39.00 now...and if a coupon is running you can get $5.00 off that and use your points from saving the codes to get a $7.00 coupon from NatureMade (500pts is about 2.5 boxes of 60) I just looked at mine, and NatureMade is Tosylate. I have never heard of a significant difference. I suspect it is only patent driven. SAMe is not stable in stomach acid, so should be enteric coated. It was only used in Europe as an injection for many years, before coming to the USA. It is best taken on an empty stomach in the morning. If you take it at night, you may have insomnia.

I recall 1 200mg tablet costing almost $2.00 when I started it, around 1999.(I remember because that was the year our son started college and I found SAMe on sale at WalMart that fall).
In fact I joined Costco just to save on my SAMe bill.

Now that I am older, I find SAMe a bit too stimulating for me.
So I don't take it as often as before. I'll do a month or two as a pulse and then stop @ 400mg a day. Sometimes every other day is enough.

NatureMade in fact was the company to develop the enteric coating when SAMe came over from Italy as an injectable. So I just trusted them the most.

You will want to make sure you have adequate Bcomplex available, and not be deficient, as B6 and B12 recycle the SAH back to SAMe in the body. SAH the metabolite (exhausted SAMe) is toxic and inflammatory in large amounts.

I really don't know about the different forms, so I can't comment on that. But make sure any SAMe you buy are blisterpacked which protects them from moisture. They will mush up quickly if not in foil individually.

SAMe is not for everyone. People with anxiety disorders or who might be bipolar should be very careful with it. I have found that older people seem to do better with it than younger. The younger set seem to get overstimulated on it. That is just my opinion.

SAMe is quite sophisticated chemically and unstable orally. That is why I only use NatureMade predominately. I only tried the RiteAid one for about 3 months or so as an add on for dosing.
The 200mg was no longer available from NatureMade at the time. Costco only carries the 400mg now.

We have a SAMe thread at the vitamin forum... it is pretty old, but goes into some detail. Use the search function to find it.