But none of them is verbatim, all of them are interpretations from AOL texts by third agers, and we cban't be sure the texts themselves truly referred to his OP raw strength and not to the power he wielded in the Shadow being comparable to LTT's in the Light. The other problem is that we know this comes from AS interpretation of AOL texts (or worse, Breaking and post-Breaking ones), and today's AS judge "power" on raw saidar potential, whereas all the signs in the series suggest AOLers also include skills when they speak of an Aes Sedai's power (they differentiate between strength and global power), that raw strength is only a factor in their global description (which only makes sense in a world full of angreal...). Mierin was as strong as any woman, yet she was only an Aes Sedai of middling power who never achieved anything worthy of a third name honorific. Her OP skills musn't be so amazing for someone as strong, she was a good OP scientist, good enough to enter the Collam Daan, but by the standards of her Age not remarkable, not enough to get any public attention for her skills. Just that might suggest she's not as powerful as LTT, that her mastery over saidar isn't enough to match his strength in saidin by higher efficiency.

The problem with Ishamael being so strong in saidin is that if he is, combined with his status as Nae'blis, it's extremely hard to understand why Demandred doesn't hate him just as much as he hates LTT. He envies Moridin's status, but nothing else. Demandred acts toward Moridin as if he is the stronger of the two.

Moridin is clearly strong, but I don't think we can be in any way certain of his exact strength, not even how he compares in raw strength to Demandred (who was second only to LTT) or Aginor (who had rare amazing skills in some areas that could very well taint his description as "powerful", unless we have a direct quote Dashiva matches Rand or almost in raw strength).