The Bitstream version is probably truer. Matthew Carter (Galliard's designer) was one of Bitstream's founders and probably supervised its digitization. The Linotype/Adobe version has also been criticized for the spacing in the italics. (I wish I could remember where I saw that, but it was a long time ago.)

Carter & Cone (Carter's current company) also has a version. It's full-featured, but it lacks the bolder weights, and looks like it's only available in PostScript Type 1 format.
http://www.fontshop.com/fonts/downloads/carter_and_cone/itc_galliard_cc/

Are you sure you haven’t got that backwards?

The ITC Galliard that I have from Adobe has an ‘rv’ kern pair of 53, pushing them clearly apart. In contrast, the ITC Galliard CC from Carter & Cone has an ‘rv’ kern pair of -16, allowing them to touch. (Note: the native fitting is different between the two versions as well.) I don’t have the Bitstream version, but I would expect it to reflect the thinking of the C&C version, for the reasons Mark explained.

The “original” would actually be Mergenthaler Linotype Galliard for phototype composition, released in 1978, before ITC acquired the licensing rights (in 1981).

But, in terms of digitizations, the Bitstream and CC versions hew more closely to the original Mergenthaler drawings than the Adobe version, which contains some modifications done during the early days of Postscript.

I am sure about the rv kerning, at least for me....The top right of the r and the top left of the v touch for the ITC version, and they do not for the BT version.....I have to blow the letters up real large to see though.