In my view, the best of the three is the Rendez Vous.
Basically they are like this:
Déja Vu has 2 LFOs (and NO envelope control). LFO is continuously variable between ramp, saw and triangle or skinny pulse, square and wide pulse. It has a modulation gate so that the LFO doesn’t bleed when in the audio range;
Rendez Vous has 1 LFO and 1 envelope follower. LFO is same above pedal. It has the same modulation gate;
Avant Garde has 2 envelope followers. It has NO modulation gate. Instead it has an LFO which can be used at the same time as both envelopes and can be routed to both sides of the pedal simultaneously. However it has a fixed shape and does not go to the extreme fast and slow speeds capable on the other two pedals so is of limited use (especially with the phaser).
I rented the Rendez Vous for a week and loved it. The last time there was a sale on I bought the Avant Garde as I thought I’d prefer two envelopes but I didn’t think it was as versatile and sent it back. I really missed having the slow LFO to direct at the phaser (or filter) and having the two envelopes wasn’t really that useful given that even with the one envelope version, you can direct it to both sides of the pedal anyway. Same goes for the Déja Vous - having two LFOs is pointless because in the Rendez Vous you can direct the one LFO to both sides of the pedal.
If you’re at all unsure, get the Rendez Vous