Ok I just finished watching the whole series of the original fma and I really liked it. But people say that the original fma is nothing like the manga.. So why make the original nothing like the manga, then make another series exactly like the manga...?
The producers of FMA started the show a little early and the manga was not finished at the time and because well manga is released once a month and anime is once a week, the anime past where the manga was in its story so the editors of the anime pretty much had to pull a story out of there @$$,

where as BH was created after the manga had finished and lots of the died hard fans were not pleased with the original show because it was nothing like the manga after epi 14 i believe or after they first meet Greed.
Now my opinion about the two different series is simple, the original was well totally original story and everything except the ending made no sense for a number of reasons. Also the original got involved with the two diff universe things one without alchemy and the other with it. Which was to realistic in my point of view they should have left that out. The series also ended on very sore note for me (including the movie) with that Ed returned met up with Al and then went back to NAW(none alchemy world) but they left the most important person behind!!! Winry WTF!!!!!! Ed and Winry were suppose to be made for one another and the original just left it at nope Ed don't get his wifey, i was very upset....Positive note on FMAO(full metal Original) is that it had a good story, kept me coming back and watching it, and got you attached to the characters, the story was strong till the end.
Brotherhood i started watching it hearing it was going to be based on the manga as close as possible with no filler episodes just a straight cut story. At first i was a little skeptical about the series it left out lots of info that FMAO had. But then it started getting better, you got more involved with Al and how he felt about not having a body, You really learned how Ed felt it was his duty to get there bodies back and that he took this burden on by himself. also Winry played a much bigger role always fixing and enhancing Ed's armor mail, you got to see the connection ed, al and winry all had. Also you got to see more about Hoenhiem. His role was played slightly down in BH but it was still a very strong role. The ending was sad and magnificent at the same time, i was on the edge of my seat watching it and was so sad when it finally came to an end. Brotherhood was a better story, the action was better i even think there was more in it, it wasn't as dark as FMA but it still had its dark points for example when Hawkeye found out selim was a homuculist, throughout the series you would have never even guessed that because they hid it so well.
Final Verdict!! Brotherhood wins by a landslide, but what i loved about FMA was if your perfomred the tabbo alchemy a homucluist was created of person you tried to bring back, i enjoyed that out of the original, but Brotherhood was way more in depth, characters were better, there was more, and the overall story told was better.