CFI... there's nothing more valuable to you right now than time as a CFI. IMHO it's a fundamental building block in the type of captain you eventually become, when you decide to upgrade one day. At that point, you're not just a PIC, but you're also a sort of instructor in the sense that you need to mentor the new FOs and mold them into safe and efficient future CAs.

As for the RJ course, let the airlines pay for that when they hire you. A TON of people get hired without taking an RJ course, and do great in training. All it takes is determination, a lot of memorization and some basic mechanical aptitude.

Good luck!!!!!