As many have said, your decision should include a number of factors. I took a minute to compile some base info based on the latest SAPA numbers.

CRJ:


1. SLC 346
2. DEN 255
3. ORD 196
4. IAH 91
5. MSP 53
6. LAX 49
7. COS 44
8. TUS 32
9. FAT 32
10. SFO 31
11. SEA 23
12. PDX 23
13. PSP 19
---
?? PHX (80?) Possible future base

Total CRJ FOs: 1194 (Hiring)

EM2:

1. FAT 76
2. SLC 50
3. PDX 28
4. PSP 27
5. SBP 8 (Unique EM2)
6. SFO 4

Total EM2 FOs: 193 (Hiring)

I personally would be careful about making lateral moves unless one of these locations looks very appealing to you. You've got starting over (and the dreaded first year pay) to think about, not to mention the possibility of things changing. Hopefully, the numbers give you an idea of the strength and or availability of each base. There really isn't much better data to go by that I'm aware of.