@PJ-Bassist Good set of Qs. My thoughts for what they're worth:
Your must have's
Octave Down - excellent tracking, I've had a fair number of octave pedals and this matches the best of them. Won't provide you with that classic OC2 tone though, but great for clean blend.
Env. Filter - ok
Compression - not my area of expertise(!) but I think a lot of folk rate the Helix
Parametric EQ - very good
Would Like to have
Fuzz - good, I've not managed to get a meaty low end yet, but messing around with crossovers and parallel loops should hopefully do the trick
Delay - excellent
Chorus - excellent
Nice to have
Analogue synth sounds - not on a par with actual synth pedals (e.g. FI, Boss SY-1)
No doubt other folk will chime in to provide you with a balanced set of views