Hello,
I'll start by informing you that I am not a B1 or B2 licenced engineer, however I do work in the industry as a Mechanical Systems Technician.
In response to your question, it really depends on personal preference - and what you would like to do as a technician. It also depends on the area where you would like to work.
Every aircraft has physical structure and an airframe, however not every aircraft has avionics [although it is the future]. Have you considered dual licencing? i.e. B1 and B2? There are many dual licenced engineers out there who I speak to on a daily basis. It obviously depends on your personal situation.
If you are aiming to become type rated on "modern aircraft" then B1 and B2 is an option, however I would maybe suggest that the B1 route has more security behind it, for want of a better term, because every aircraft type requires the B1 skillset.
Again, I am not a licenced engineer, so I don't know first hand. I sit in an office and provide technical solutions to the hands-on guys for problems not covered in manuals etc.
Good luck with whatever you choose.
All the best.
Doc