Undercity or Altar?

[LordJanova]

I'm building a token and sacrifice EDH deck and I want there to be a possible mill win con with either {Undercity Informer} or {Altar Of Dementia}. I like both of them a lot but I can't decide which one to use and I don't want both in the deck. I think the informer will be the most consistent as I'll only need to sacrifice between 33 and 40(sometimes more) creatures depending on the deck whereas with the altar I need to sacrifice creatures with power totaling probably around 70-80 ish depending on how far into the game I draw it, and that 70-80 power could be a lot of creatures potentially, so where the informer will only ever be the amount of lands in their deck the altar could be more, and the informer could kill them a lot faster if they are pulling lands out of their deck a lot. But another thing is that the informer needs a mana investment to use so I could be limited in how many times I use it each turn leaving them opportunities to kill it on their turn but the altar doesn't so I'm only as limited as my token creation makes me and can use it enough to kill them the turn I play it, which is not limited at all there will be a lot of tokens and if need be I can sacrifice a super huge mycoloth to the altar and make them mill a lot to end the game. So there are a lot of pros and cons to each and I just want you guys help figuring out which one to use.

[Dudecore]

I prefer Altar. While undercity has a bigger effect, Altar is cheaper and has no mana requirement

[The1337Magician]

[Spikepit]

Ooooooh cool!!! Who's your commander? What else in in it? Are you using reanimates too? I love sac utility decks!

[LordJanova]

The commander is {Prossh, Skyraider of Kher} and I'll post the deck list once I'm done with it.