I use three of their Vocal FX pedals. As others have said, the Mic Mechanic is a genius piece of kit, a complete no-brainer.
https://www.thomann.de/gb/tc_helicon_mic_mechanic_2.htm?sid=ff967fac4f3e0d4153656bbc9f6d772d
When I'm mainly singing BVs in a 3-piece, I tend to use this instead:
https://www.thomann.de/gb/tc_helicon_duplicator.htm
Basically it's a Mic Mechanic with the Wet/Dry control replaced with ADT to thicken up my voice.
With my rockabilly band, where I frequently have to do the whole Jordanaires thing, I use this:
https://www.google.co.uk/shopping/product/10836893526893741269?lsf=seller:291943,store:17486815475102514008&prds=oid:9052323143970673685&q=tc+helicon+harmony+singer&hl=en&ei=UYfoXp2SMJKp1fAPyfCI0As&lsft=gclid:CjwKCAjw26H3BRB2EiwAy32zhT9lJ5x6XCQFak-py0xPN-cXmpT9Wki50qatAAYt2L_pvWfkF7kuNBoC2a4QAvD_BwE
Those big VoiceLive modules assume that you're happy to fiddle with the knobs or scroll through a tiny LCD menu between songs. I know that a lot of people are very happy to do just that, but I'm strictly Fire & Forget ... for me the pedal is either on or off.
The closest I get to knob twiddling is on the Harmony Singer, where I'd love to use the input from the bass to provide the key automatically but playing double bass live in rockabilly leans towards dodgy intonation, and dodgy intonation with one of these harmoniser pedals has to be heard to be believed.