While I support you putting PIC TURB on the top of your list there are a few things to consider.
Do you meet all of the other minimums for a legacy new-hire? Degree etc? If not, then I'd say work on the degree as you log PIC TURB. That job will give you a lot of time to study and complete your BS Degree.
1. Networking. If you go to the regional, you'll have the opportunity to make a lot of good contacts. These contacts will eventually migrate in a hundred different directions. This will open doors you never even seen before. Additionally, this job may help you get the letters of recommendation you'll need later on for the "Legacy" carriers but then you'll need about four years or so of "networking" to get senior enough to upgrade and log the PIC TURB.
I'm a major cargo pilot. In my new hire class, we had 24 pilots (12 Mil/12 Civ). Of the 12 Civy pilots, two were prior enlisted. Two others were "Heavy Corporate" (Gulfstream types) with international experience while the remaining 10 Civy pilots were all regional jet pilots. Everyone had a 'sponsor' and several other letters from the inside. As you can see, the Regional Pilots were able to network their way into the class. Out of all of the 24 pilots, only one had NO JET TIME. He only had turboprop time. He had completed an internship with the company and was a PC Check Airman on a Dash for a large regional. Statistically speaking: 41.6% of the class had RJ time. That increases your odds!
I also think the regionals safety record "may" tank. If the legacy carriers keep hiring, there isn't a sufficient pilot pool to draw from in the instructor ranks to fill the regionals. It's possible that you could be paired up with a 23 year old captain with 1500 hours who sat in the right seat of a SAAB and upgraded to the CRJ. This guy could be paired with a 300 hour FO coming from ABC University's ab-initio program. This isn't a recipe for disaster but it certainly could add some increased risk to the safety record.
If this movement continues, if you have a lot of flight time, you might receive an earlier upgrade and thus might log PIC TURB sooner than the average new hire.
2. Another factor that is most likely going to effect retirements at the legacy carriers - the age 65 rule. If that rule becomes law, the legacy hiring may briefly stagnate. Thus regional hiring may stagnate as a result and thus your upgrade to captain. It's hard to say how this will play out but the odds of many legacy pilots hanging around another five years to help restore some retirement is real and likely. Thus, this is an argument for the Cargo TURB PIC job. It's a tough call but there are the pro's and con's. I guess it is up to you. If you pick captain, you'll be making a lot of decisions like that over the next year.
3. From what I've heard, if you feed FedEx, I doubt FedEx will hire you as it will hurt their partners. You might look into another webboard -
www.usfeederpilots.com That is a board specifically designed for cargo guys that feed the Purple Tails.
Looking at the big picture, I'd say you have to decide what is more valuable to you.
Personally, if you're an older guy and have quite a bit of flight time - The PIC TURB will open many doors that SIC TURB will not. If the major's put hiring on hold due to some terrorist action, then you're better off with the cargo. Personally, I'd go for the TURB PIC. If you're a young guy with more time to spare, the regional route might be a good choice. All in all - you can never go wrong with PIC TURB. If it is likely your new NICE CP is going to stay, then good on ya. If it is likely he/she might move on and another less desireable CP take his/her place - then you might want the union protection offered by the regionals. You're more insulated from the tyranny of bad management at the regionals in comparison to a smaller company.
My .02
Major Cargo Pilot