You should get.....

What is the maximum delay time on it?

I am using a Zoom 508 which goes up to 4 seconds and has a ton of incredible presets.

Line 6 makes a less expensive pedal...ECHO PARK. It has the tape/analog emulations of their larger pedal without the minimal looping capability....and a lot cheaper (I use it) Love that wow/flutter!!

The Line 6 delay modual is awesome. I have had it for years and it is probably my most used pedal, but thats with guitar. It does sound really good with my theremin though. I also have a Digitech reverb pedal that has some really nice verb sounds. Smooth hall and Church sound. They also have a pretty realistic Spring reverb sound on it. But some times I just like my theremin dry.

I switch around between various effects and totally dry for that classic theremin sound.

dry is the way to go, when i had a b3 i used a metalzone to make a more harsh thick sound because the b3 has no tone adjustments, but now since i can make tone adjustments its always dry