Hard call...my favorite used to be the ABS "Super Glove", with kangaroo hide. They no longer offer the kangaroo (incredibly tough leather), and moved their manufacturing facility to China so the quality just isn't the same. I still have 3 or 4 of the old ones, so I'm set for several years.
American Leathers gets good reviews, as does Bateman. They aren't cheap, but look to be well made.
I won't order a glove through the mail--just can't get a good fit that way. Besides the size varying a touch from one to the other, leather itself can vary. I have to try it on before I buy, even with places that tell you to send in a trace of your hand (tried it--waste of time and money).
When buying a leather glove, I want one that, when new, fits so tight I can barely shove my fingers into it. That way, when it's broken in, it fits just right. If it fits good when new, when you break it in it will be loose.
Products like Montanna Pitch Blend, Sno-Seal, or most any good leather treatment will help speed up the break-in process, and help protect the leather as well.
Chad