I would go 121 if I was you... it is true that 135 is sometimes considered to be less of a good background, however realise that most 135 air carriers are little by little getting to have to meet all 121 standards. Possibly, in the distant future, 135 will no longer exist, all carriers will have to meet 121 standards.
xxx
Another suggestion, yes, go for cargo/freight operations...
When the economy goes bad, the first thing is passengers stop travel, as they cannot afford vacations, and businessmen do not buy travel tickets, they use the phone rather than spend money on airlines and hotels. No matter how the economy is, freight still must move...
xxx
In the bad economy periods of the past, air cargo never showed much reduction in volume... Not the same with passenger airlines...
All the best to you -
Happy contrails