Either/or
Why can't you do both? 135 time is closest to the type of flying done by the commuters. It helps greatly if you can offer experience that closely matches what they want. You can still instruct.
Having said all that, I second Deftone. I usually come out very strongly in favor of instructing for new pilots, primarily because it is a valuable learning experience in more ways than one. However, rare is the 135 job for a lowtimer and perhaps you should jump on it. But, not to the complete exclusion of instructing.
Bear in mind, though, that multi PIC along with total time is what you really need. Seek out those opportunties as well.
Good luck with your decision.