Bigger systems: Blueline or Iwaki
Smaller sys: Ehiem, Magdrive, Vectra
Best bang for your buck is going to be reef octopus hands down, I like Vertex as well
Schedule 40 or 80
finnex titanium/ranco for bigger tanks
Ehiem or Cobalt Neotherm for smaller setups
BRS = best bang for your buck
Vertex if cost isnt a big issue
DIY with server wire racks
Dosing: Calcium Reactors/Kalk Reactors/Dosing Pumps
Calcium reactor + kalk stirrer (geo, korallin, Precision Marine, MRC)
Monitors/Controllers/Alarms/Warnings/Notifications:
Apex, mostly for monitoring.
Water Top Off / Water changes:
Tunze osmolator, wont ever trust anything else personally.
Mechanical Filtration: Media/Sponges/Filters/Rollers
If I can't commit to changing socks every 3 days , I don't use them, if room/cost was not an issue a roller mat would be ideal
generator
Depends, on longer big tanks 5ft+ Tunze stream pumps.
4 ft or shorter I prefer Vortechs
Just my .02