Don't know how deep your pockets are but I'm sure most would say Eheim is at the top of the list. Rena/Filstar, PennPlax/Cascade, Fluval also make some respectable products. Some will swear by one & curse all others but that's the hobby!! Some have workable combinations of different filters to suit their needs. At the 'end of the day' it's 'pick-em'!!
i like fluvals and for biological a biowheel pro system. not a biowheel filter (penguin or emperor), but they make a biowheel that is just the biowheel powered by a powerhead, also comes with 2 biowheels from one powerhead. biowheel is the best biological and with the fluval you will have great mechanical and chemical. i have fond no problems with the fluvals over the years (at least not any that werent fixed with the new 05 line of fluvals) so i dont see a reason to go any more expensive (not that fluvals are cheap, but they are worth it).
Eheim is supposed to be the best...but is also the priciest.
I have 2 Rena Filstars and feel they are the best value...work well and are more economical.
I've had experience with Fluvals and Eheims. I bought an Eheim about 15-20 years ago and it still functions perfectly. My current Fluval is about a year old and still running well.
I started with a Penn Plax then bought an Eheim Thermal Pro. Then I bought another Eheim Thermal Pro, and another, and then a Pro 2 2028 ,and will be buying another Eheim Pro 2 soon.