Head height matters. And if you have a max of 1.75 and you are liftinh 1.5 you will have pretty slow flow. You can raise the output if you raise the canister higher.
That said I have 34 canisters all are Eheim. I bought two used tanks over the years which came with Fluval canisters. I sold those canisters chaeply to replace them with Eheimms. I got the Pro II series which is long outdated and not made for a long time. All three are running fine and the one over 20 years I just closed down the tank.
The first 10 years that filter ran I pumped pressurized Co2 into the intake. The filter was as quiet 20 years later as the day I got it. I bought my last one on Ebay NIB after they had been dicontinued.
I wanted nothing to do with Sun Sun, Aquatop of Fluval as I consider that like buying a cheap Chevy instead of a Mercedes.
I am not sure where they now make them. I know the Classic line is made in Chona, so even though it has the Ehaim name I would not want on. But I know that the other models were being made in Germany or elsewhere in Europe 5 years ago, I am not sure where today. I believe Fluvals are made in Europe, it used to be Italy but may now be more spread out.
I prefer if possible not to buy anything for tanks from Chine when possible. I am willing to spend more if needed. So Sun Sun is not on my list. I use Aquatop heaters which break just as often as the other brands. Heaters are the least reliable equipment we use, IMO. Aquartop may be made by Sun Sun as far as I can tell.
And do not kid yourselves, China products have degraded the same as those made elsewhere. But I have Eheim Pro II canisters ruunning from between 12 and 20+ years with minimal issues. head gasket here and there and a few of the tiny parts between the trays that eventually wore out. Thye are a couple of dollars iwhen they do, I often get my small spare Eheim parts mailed from the UK and they come fairly fast. One of those 2026s I got on EBay NIB was intended to used for spare parts. By them they were on to higher number models.
I am one who likes to keep things simple. I do not want almost anything digital for my tanks aside from some of my testing equipment. I had that cars are digital as it is almost always that sort of parts breaking morso than the mechanical ones. Heck, I even dislike anti-lock
breaks.
p.s. It is alright to have floe contol on a filter but it should be on the output side not the intake, The filter needs to be filled when it runs and if we slow the intake and that allows air to accumulate inside the canister, it can cause problems. this is also true for poerheads and pumps. If you close of the output and motor still runs at full speed but the output slows things, Impede the intake and that can reduce the water level inside the unit. I was taught this about 23 years ago by a fishkeeper whose job was working with immense pumps use in huge installations, not the "toy" one we have.