Well they always recommend 885's with a double cab since the extra weight. 884' are mostly made for the access cab Tacoma's. I have 885's on my 5100's set at 0" and I got a full 3" lift out of it with the top plate spacer.
The only reason i'm considering the 884's rather than the 885's is because I don't want a full 3" lift. I'm aiming for 2-2.5" max of lift. I won't be putting in UCA's, so close to 2" of lift would be ideal to keep alignment specs reasonable while trying to avoid issues down the road.