My opinion of Juwel;
Tank itself is excellent.
Filter is great on the smaller models, but lacking on the larger ones
I have never had issues with the heaters, but they are harder than most to set the temperature on.
Lighting is fairly limiting as far as plant growth goes, but otherwise OK. The first Juwel T5 lighting units ware appalling, lasting on adverage between 12 seconds and 12 days before failing hard. On such unit nearly set a customer's house alight

I wasn't overly supprised to hear him asking the manager for his cash back...

These lighting issues have apparently been fixed, as all complaints of faults on the recent tanks have dropped back to the usual minimal rate at my place of work...
The stands are very flimsy if you ever dismantle for moving, made of chipboard. You'd be better building your own IMO
Overall, they are good IMO, with my Record 98 lasting 5 years before being sold on. It's still going strong with the only replacement part being the tube from origional

If you are wanting to grow plants, I'd bin the lights, and add an exturnal filter to the larger tanks. Otherwise I like them.
All the best
Rabbut