moontower is basically synthy rush with death growls which in a way limits its appeal to both dm fans wanting harder riffs and non-dm fans who hate growls
Moontower is certainly a unique listen and it is a shame that it only really appeals to a rather niche audience.
I haven't heard of 13 until about a week or 2 ago but it is already one of my favourite heavy metal albums. It is filled with many tasty riffs and solos.