I tend to think Lews Therin was made the First because of his leadership abilities - he seems to have had some rare Talents, but none of which were as impressive as the skills possessed by the Forsaken and some of Rand's Third Age companions. Perhaps he was a consensus builder, and a capable leader (ie: somewhat like a Blue Ajah Amyrlin - one of their greatest Sisters was considered to be Eadyth who was said to be "one of the most capable Blues in the last one hundred years"...as an Ajah, they seem to prize versatility). Because choosing your leader on the basis of One Power strength doesn't seem to gel with their society, in which strength wasn't as important due to the uniquitousness of Circles. If people referred to leadership qualities, I'd not raise any objections, but the reasons people trot out for Lews to be awarded "Best Man Ever!" always have to do with Talents, OP strength and t'a'veren status - none of which have anything to do with his personality or skills.

That said, Ishamael still lurks somewhere in the evil supervillain category. Basically, he sucks. And I haven't seen anything to prove otherwise. His whole backstory revolves around being defeated again and again - we don't even have any stories of his successes, unlike the other Forsaken. The only "success" he had was turning Hawkwing against Aes Sedai and the formation of the Black Ajah - both of which are rather lackluster in comparison to Lews Therin, Latra Posae or a Rashima Kerenmosa.