I know you asked Todd and he'll respond for sure but I'll jump in because this is an interesting question and it's something I've asked Todd about in the past.
I know Todd will tell you that you can't go wrong with Ray Brown, Ron Carter or Paul Chambers although I suspect he would have you start with Ray Brown.
Most importantly, and something Todd shared with me as well, it will make a HUGE difference if you go after a particular tune or line that really appeals to you. Definitely we need to hear from guys like Todd and take their advice to give us a direction to start in but we get much more out of a line when it's something that catches our ear and appeals to us.
Personally I got really turned on to transcribing by Todd and I started transcribing blues first. I went after lines I liked and gravitated towards players I was really interested in at the time. So I transcribed Ray Brown, Doug Watkins and a ton of Steve Swallow in the beginning (all of them playing over Blues). Then I started moving towards songs/standards that I really wanted to learn.
Oh yeah, another thing, of all the times I've seen Todd play I've never see him anywhere near a Fakebook. I wanted to be like that also and have all these tunes internalized, so I never approached any of them with Real Book or chord charts.
It's fun, it's addicting, and I think my playing has grown tremendously once I started transcribing and internalizing all of these lines.
Anyways, Todd will give you the straight scoop but I wanted to chime in because it was Todd that told me I should really start transcribing about a year and a half ago and I was very intimdated at first and put it off for a while. Once you get going, your confidence builds and you start to feel like you can tackle any song out there.
Oh yeah, get Transcribe!
Free trial for I think 30 days or something.