God I love that band. To me, and I know 95% of the world will disagree but anyways, APC is way better than Tool. Tool to me is a band with some epics (Wings for Marie: 18 minutes long and doesn't bore a second) but Tool never made an album on which I didn't hear a single mediocre song. APC's Mer de Noms is one of those albums where it's just spot on from the first to the last second. Also, songs such as The Hollow, Breña or Orestes are up there with the best songs Tool did. I love Maynard James Keenan's vocals, but must admit I am very fond of Billy Howerdel as well and the ethereal atmosphere on Mer de Noms (intro's of Breña, Orestes, Magdalena ...) does the trick for me.
Anyways, a band that makes me think a lot about Tool is The God Machine, about whom I opened a topic
here. They make a mixture of noise, metal, industrial and prog rock with very lengthy songs, gloomy lyrics and complex structures. And even though his voice sounds nothing like Maynard's voice, Robin Proper Sheppard is an amazing vocalist as well. TGM were forced to call things an end when their bass player died from a brain tumor but the two albums they made were epics (especially Scenes From The Second Storey) and if they were not confrontated with the disaster of bass player Jimmy Fernandez' dead and had the chance to release some more albums, then they would have been in the category of Tool IMO. I would even say The God Machine are more intense than Tool, but that's just my opinion and I am very fond of both bands and also of A Perfect Circle.
The only thing Maynard ever did which I disliked is Puscifer. Not my cup of tea at all. I wish he would split his time between Tool and APC again rather than filling empty days in the agenda with Puscifer.