I love Hellsing. I started with the TV show, got into the manga, and then saw the OVAs. One thing I thought dragged Hellsing Ultimate down though, was its soundtrack. The TV show was really eclectic and interesting- gave the show a "Tarantino does vampire hunters" feel. Ultimate's just feels so...generic by comparison.
So many people seem to love the TV show's soundtrack and I don't know why. I've always thought it was one of the weaker points of that version. (But then my favorite music genre is Ska so what do I know?) Sure the TV show's opening theme is memorable, but I'd contend that
Hellsing Ultimate's main theme is just as memorable, but more subtle. It comes down to the difference between the manga and OVA's emphasis on action and the TV show's tendency toward gothic-punk creepiness I suppose.
In my opinion the Warsaw Philharmonic Orchestra performing "Merche Fuenbre" at the end of OVA 2 is one of the high points of the franchise as a whole.
I'm a hardcore Hellsing fan and I still think that piece of music may be almost
too good, or at least too classy, for a series that inspired the "Party Hard" style image "Nazi Vampires Eating Babies!"