Very open ended question, and keep in mind we haven't even seen the first release of a "real" campaign yet, just the shorty included in the core set. So, umm, hard to know what to say
By the time we DO see a full campaign we'll have twice as many investigators too, actually more I guess if Marie Lambeau is out by that time.
Normally you can't get more than 1 trauma per scenario so it takes consistent bad runs to actually kill off an investigator. I guess you can say that anyone with severely unbalanced stats is at more risk. Personally, I'd go more with whatever investigator works well for me. In my case, playing solo, I feel more confident with Agnes and Skids. Then Roland and Daisy, then Wendy. Others may have different playstyles, or it likely varies when playing with bigger groups - solo has its own considerations since you have to cover everything with one investigator.
And finally, even if there was an answer to the question, what would that answer be good for? I'd rather run the investigators I like than pick someone I don't enjoy just because they might have a couple percent higher survival rate.