personally I like the tesseract tex-mix over the wmd performance mixer - it's significantly cheaper and more expandable and uses less power - I'm sure that the performance mixer is exceptional - but it is big and expensive and power hungry...
the advantage of these over the cockpit is that they have panning for mono sources to stereo, in the case of the wmd pm, this can be automated with an lfo*) - which allows you to put a mono source in the middle, fully left or fully right or somewhere in between - if you only have stereo inputs - then you only get the possibility of fully left or fully right - or both if you mult the signal (and then recombine using a special cable in the case of these cockpit modules)
the only "advantage" of the cockpits I see is that they have ducking - although imo this is better patched using envelopes, an inverter/polarizer/attenuverter, a small utility mixer and a vca - ie "modular synthesis" and not just "synthesis with modules"...
I see the 'mono/stereo/ios send/return' nature of these mixer modules to be a complete pain in the arse... I seriously would not want it in my rack... I'd be loosing any adapter cables in the pile of patch cables and/or confusing stereo cables with regular patch cables and wondering why my stereo field was competely shit constantly - ymmv, though
the cockpit modules only really stand up in a endorphin.es only set up and if you are willing to separate audio and cv - which is one of the advantages of eurorack over some other formats, in that it doesn't do this...
BUT saying that either way you need some smaller mixers like the 3*mia or shades or whatever - to use as sub-mixers... and then you get back to the mono/stereo patch cable malarky...
also at least one filter is a good idea - there are so many available and they are so personal, that I find it difficult to recommend them - I have a couple of ripples - which are rolandy/vanilla, various doepfer ones that are based on other classic filter designs (wasp, sem, moog) and a couple more - but they all impart their own characteristics and it's impossible to say x is better than y - as it's so personal - there are plenty of filter shootoout demos on youtube, which should give you a basic idea - what to look out for
*you can do this easily with a mult, a couple of vcas, an lfo and an inverter - if you want to patch it when needed - or buy cv-able panner modules if used constantly
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities