When the River Runs Deep is seriously my favorite song on Book of Souls. Gone are the repetitive riffs that go on for bars too long--the tempo changes come and go in a natural flow--that weigh down so many songs from Where Eagles Dare and on. The chorus and bridge actually have different words in them (i.e., the chorus is not When the River Runs Deep eight times in a row). The solos rip and the flourishes within the verse and throughout the song are compelling. Bruce is not perfect, but his delivery has a snarl and the delivery runs across the melody, rather than trying to keep up with punishing riff (see the song Book of Souls). Nicko's drumming is on fire and the cowbell is a nice flourish. In short, what I live about When the River Runs Deep (and this extends to another song semi-marginalized by Maidenfans: El Dorado) is that it sounds alive, like a breathing animal, straining against its bounds, to lurch out and destroy...(check the lyrics)...fish.
Fates Warning is one of those songs that I hear people too often say, "it's overlooked, seriously have you even heard it lately, or try it again, it's really under-appreciated." I literally can't even remember the song without listening to it (which I do every time these debates come up) and even then I forget what it sounds like within days. And I bought No Prayer for the Dying on the day it was released (before noon, because I was so excited for it).