The majors aren't hiring many pilots from small cargo operators. The quickest path is probably to crank out as many hours as you can and do what the majority ahead of you have done, go to a regional ASAP, upgrade, and hope you get hired. Or you can go to a AA WO'd regional and wait for the flow while applying to AA/DL/UA/FX/UP etc in the meantime.
The typical civilian guy had 5000-7500 hrs. Since you're not at a regional now I'll assume you have 1000 hrs TT. At 800 hrs/year in 6 years you'll have 5800 hrs with roughly 2500 hrs 121 TPIC. Flying 500 hrs/year at the cargo job will get you to 4,000 hrs TT with zero 121 TPIC in six years.
It's not about what's the cool job tomorrow, and the better pay check, or better place to live, it's about what gives you the most competitive resume, the quickest, for your final goal. IMO busting your butt as a CFI, then flying as much as you can as a regional FO, then CA, and hopefully a CKA, is the best path out there.
If you don't go to a wholly owned regional and with 1,000 hrs 121 TPIC in your logbook and no hope of CKA in the near term (1-2 yrs), at that point I'd consider going to an ACMI heavy cargo job and gaining another type rating and experience in a larger jet doing international operations.