Best cheap/natural-sounding hardware vocal FX processors

Hey, guys!
I've got a concert event *possibly* planned for my church that we'll be putting on in June.It's really a full-scale concert with 10-or-so pieces from group ranging from classical flute quartet to gospel choir to full-on concert wind band.
We're planning to build a portable sound system from the ground up, more or less, using a Mackie 8-channel mixer as the main mixer module, my PreSonus Firepod (offline, as a way to add more inputs), plus a plethora of microphones and a pair of PA speakers (those logistics as far as micing and things will get sorted out, as we just began tossing the idea around two days ago and aren't even settled on a program yet).
 
And so, what we're looking for, naturally enough, is a decently-realistic sounding, low-cost reverb processor.
 
 
I thought first about running it all into Garageband, for instance, and then the mixing guy can steer the sound system on an iPad remotely, but there's no way I'll get a Mac fast enough to do that JUST for that day (and my Macbook certainly can't handle the number of inputs AND effects per-channel that we're trying to do), and it'd have to be tested weeks beforehand. Not to mention the dangers of latency and whatnot, so we're not doing that. I have also a BOSS BR-532 that works pretty darned well as an external FX processor, but it's TOUGH to dial in ideal settings for avoiding clipping vs. still getting a high enough output level, so that almost seems like an idea to be avoided.
 
Basic EQing can generally be handled on the Mackie. This is our first time out, so I'm not expecting people to be looking for an absolute perfect 'sound image' right off the bat. 
Definitely looking for recommendations regarding this set up too!
Thanks!

Behringer made/makes a decent sounding (rack-mount) multi-effects processor that includes some decent reverbs.
I think these go for ~$129.
 

that looks pretty sweet!
 

Cactus Music
https://www.sweetwater.com/store/detail/MX200
 
This is my recommendation. It sounds amazing and gives you 2 channels so you can stack Reverb and delay.
 
 

+1  I owned one of them when I did Live sound.  The reverbs are superb and the delay.  Let's just say that the one  part in "Footloose" with the delay sounded awesome!

Way back in the 80's my Atari played my midi files and controlled my Alesis multi verb and Roland delay units, I miss that ability to have custom effects for each song, and ya, I used lots of special effects to accent parts of songs. 
I bought the Lexicon knowing it would probably have top notch effects and all reviews were good with only the complaints about the software being negative.