I'm a bit new to Vintage and very new to TMD so I hope I'm 'doing this right'.
It seems like library and bob are better than each other in certain situations. For example, when you're running 4x force 4x gush 2x JMS 1x Dig you break even and even save life using library to find them, and even with Dack and Mentor you only effectively lose 1 life vs drawing them with Bob. Complete opposite with 1CC draws, counters, or other interaction, you much rather draw it with Bob than choose to keep it with library. So it seems like library vs Bob is more about playstyle and deck build than one being strictly better than the other.
Since this is the Sylvan Mentor thread I'd assume that Sylvan may be strictly better here because, so far in my experience with Rich Shay decks, I have seen them to be much more methodical game plan+card advantage oriented than aggressive+card advantage which is where I think Bob fits better.
Anyways, TMD has been a godsend for me over the last few months and this community seems amazing! Thanks to all involved moving it forward!