Depends on your goal
Different companies have slightly different requirements and you may have to decide a path that will be appealing to your number 1 choice but yet make you competitive for others that appeal to you. For example, if you want to go the SWA, you probably want more PIC turbine time. If you want to go to JetBlue, you will need an aircraft with a Higher Max Takeoff Gross Weight(>20,000 lbs). Since you have the Part 121 experience already, going to a Part 135 jet operation as a captain, might be a good move by getting the PIC jet. If that aircraft happens to be a Hawker or bigger (>20,000lbs), then you make yourself competitive for JBlue and SWA both. I would go to a Regional for the RJ job, if it was one where I thought the upgrade would be relatively quick (less than 2 years) ,otherwise, stay away from it. I had the same dilemma about a year ago and went with the PIC jet part 135, best decision ever...However, I do not have the Part 121 experience and I am excluded from companies that want the 121 experience (like Airtran, etc...). But these are choices that we make and we live with the consequences.
Oh well ... decisions, decisions...Good luck