CXX definitely has more memory than Siege.  I spooled my daughter's baitcast reel with 12# CXX because she fishes a Senko all the time.  (Doesn't get out much.)  She complained about casting problems due to memory.  I re-spooled the reel with 12# Siege.  Hasn't complained since.

 

I'm like michaelb.  Lots of good lines...not enough time (or money) to test them all.  I also use 12# Big Game.  Little more memory than Siege.  Works well after getting wet.  First few casts I can get fluff on the spool if not careful.  Siege, no.  However, the first few casts with Siege has the line in front of the reel looking like a slinky.  Doesn't fluff on the spool, tho.

The followings are available in my local stores and the diameters are actual, in the order of strength/(mm x mm) and abrasion:

CXX 10#: 0.38

Izorline Platinum or XXX 12#: 0.35-0.36

Yo-Zuri Hybrid 12#: 0.35