Perfect Viewer is easily the best, by far. I'm not familiar with the IOS comparisons although to be honest, but I"m basing my findings after installing all the various readers one night and just going through the various likes/dislikes.
The only downside to Perfect Viewer is learning the touch map hotspot layout, not accidentally hitting them. The bookshelf is very well done and clean. It also seems to be the most stable of the readers. The biggest offense to me was not having a bookshelf, which many of the other readers did not have or worked smoothly.
ComicRack seemed to be a great alternative, but it simply wasn't as solid of a reader in terms of crashing. They don't have OSX support as well. The idea is to be like iTunes more, where you load your comics up to a computer program and have them sync to your device over WiFi or direct connection.
Does Perfect Viewer support the likes of Dropbox and Skydrive?