I take "natural" or bio-identical progesterone. I have never taken synthetic, so unfortunately, I don't have that kind of relativity to help you.
I started my program about a month ago -- so I am not really getting the full benefits yet.
I did a ton of research regarding the difference btw natural and synthetic. For me, bio-identicals were a better choice to reduce my high estrogen levels.
First of all -- although I wish there were more studies, overall -- Bioidentical hormones are associated with lower risks, including the risk of breast cancer and cardiovascular disease. For this reason, I got the impression that most doctors prefer to start off with bio-identicals, and if they work, great, and if they don't, then they move onto to synthetics.
Additionally, I read a study regarding the use of bio-identical or natural progesterone creams and their effectiveness. The bottom line is that the "transdermal" creams may be less effective because too little of the progesterone is able to be absorbed through the skin.
So, if you have a serious need for absorption -- e.g., if you are like me, with crazy high estrogen levels and all the wonderful problems associated therewith -- it may be better to take the pill form. It's a hassle to get a prescription and find a good compounding pharmacy. But it's worth it to me!
Anyway, I take my progesterone before bed. And wow. I sleep so much better now! It's almost like taking an Ambien. No more waking up in a pool of sweat.
BTW -- I started taking bio-identicals in 2008 or so. And then I quit after a year or so. So this is my 2nd tour.
In 2008 -- I was having all kinds of issues -- endometrial thickening, polyps, cramps, constant bleeding. My OBGYN wanted me to start synthentics. Or get a partial hysterectomy. (I still roll my eyes at that one -- taking my uterus would not balance my hormones. Yes, I would not have a period, cramps, polyps -- but I am pretty sure I would still be a hormonal wrecking ball with a new set up problems, and 20 more pounds on top it. )
Back then, natural hormone treatment wasn't as common -- at least in Texas. It was something only health freaks like me did! Anyway -- after months of treatment with bio-identicals -- I told my OBGYN. He was so angry with me! He scolded me and told me it was "snake oil" and that I was being victimized by "scammers."
I stopped taking them that day. And in 2014, after two failed ablations, 20 lbs gains, and an estrogen level that has skyrocketed while my progesterone is basically non-existent -- I am back on bio-identicals. And I bet that same OBGYN is now prescribing natural hormones. (It is clearly the new "thing" -- clinics popping up everywhere. Lots of money in it I imagine.)
Anyway -- let me know how it goes for you!