What price range are you looking at? I bought the $140 Ovation bridle off of SmartPak a couple of months ago and it is very dark (almost black), and very nice for the price IMO. Definitely a big step above other bridles in that price range.
I haven’t seen the Voltaire bridles, but I do own a hunter girth by them and the leather is very soft.
Aramas is another great option as well, and very nice for the price (probably also one of the nicest in its price range).
If you can find a Jeffries, those are beautiful, sturdy, and available in a chocolate color, which can probably oil darker.
Stübben might also have something as well, though I’m not sure how “hunter-y” their current offerings are.
Bobby’s might have something in their Signature Series as well, though I’m not sure what their quality is like anymore.
I believe Huntley might have a dark bridle too IIRC, and I’ve heard a lot of good things about those. I think a few people here have purchased The In Gate bridles and had them oil up to a pretty dark color.
Nunn Finer may be one to look into as well, though I haven’t seen much of their hunter bridles up close. I know people who have them and like them, but have never handled them, myself. Their Bartville-made stuff is nice, though I believe their hunter bridles are made elsewhere.