Mimeophon - feedback looping and crazy stuff
Sealegs - delay and end of chain processing
Aurora - spectral fx and whale singing
beads - flexible allaround fx, delay, stutter fx and granular

the next could be the Plexiphon, if I get it into my hands
-- VONDENFUNKEN

Off-topic, but what is up with the Plexiphon delay? (delay as in "arriving late").

I like (in no particular order):

• Indian Resonator (Error Instruments) - when Rings is not enough
• Echo Cinematic (Knobula) - wonderfully ambient looping
• Desmodus Versio (Noise Engineering) - oldie but goodie! shimmery tails are needed
• Nautilus (Qu Bit) - interesting LFO produced along with the FX
• Meta (OX) - lots of FX in a small package

and plenty more that don't come to mind atm.