I use Cobalt 7-String Skinny Top Heavy Bottom they're 10-62. 9' feels to thin for me, I was always afraid that I'd break the high E string It's all about feeling and your personal preferences. No technical rules for this
I use Hybrid Slinky on my JP7.
09-46 set with .60 as low B. That way I get the easy bending from .09 set and the bottom groove from .10 and feel the .60 as low B give the tightness I need.
I use Regular Slinky's 10-56 on my 7 string. I have mine tuned in Eb standard, basically a half step down standard tuning. Also, I mainly use 10's on all my guitars just because of playing and feel preference. I used to play with 9's but they started to feel to thin for me.
I use a Hybrid Slilnky set, which as Fretter said is 9-46, and then I throw on a 56 for the low B. That way my strings go 56, 46, 36, 26, 16 and or course 11 and 9 for easy bending. I like the consistent decline of 10 for the lower strings, just feels right for me.
I recently just started using the 11-58 cobalt set in standard with a low a. I really dig the tighter tension. My other guitar player switched to the same set, too.