I have just gone through what you are doing. I can give you my 2 cents ( pence in your case )
I have a 29g tall and a 125g 72" wide tank(s), both are planted community.
29g is low tech lighting and the 125 gis high tech LED
Filter debates will go on till the end of time.
The flow rates on all filters are marketing B.S. I think they are measured flow with empty canisters. When filled with essential media, you get what you get, depending on what you put in the canister ( much lower flow rate, which is good for nitrifying bacterial growth)
i got an eheim 2215 right from the beginning, and it has been flawless. Silent, crystal water and excellent filter. As their classic design, the canister is not as easy to clean as filters with trays, but the time difference is not more than 5-10 minutes, in my experience; but works very well. The best part is that the design is very simple.
For the 125g :
I started with a fluval 405, it moves water and has an easy means of cleaning. The hoses are corrugated and made of thin wall polyethylene. They are flimsy but are easy to place. The corrugation are a haven for gunk growth ( due to the increased surface area)
I was not able to get the tank crystal clear no matter what i packed the filter with.
I switched to Eheim ( Pro3 ) and it was pretty good, but i had a lot of bypass around the media. I liked the filter, but was not "Amazed."
I added a Sunsun 404 ( very cheap and cheerful ) and it works well. Knowing that the size was inadequate for my tank, I knew I needed to get an a secondary filter.
I got a wild hair up my backside and I bought a monster Eheim 2262 (basically a 5 gallon bucket with a pump on it ) Great filter for a 300 gallon tank, but not so, for a 125g. It was not silent, but pretty quiet, and it raised the water temp in my tank. Not bad for cold Colorado winters, but bad for warm summers. The tank was amazingly clean and I needed to make a custom spray bar to prevent a river like flow of water.
I returned it and bought 2 Eheim 2217's to work with the Sunsun 404. The tank is crystal clear with no regrets. I have enough beneficial bacteria in all filters to prevent a problem if one is out of service.
The SunSun is a much lower flow, than the Eheims, which is great for nitrifying bacteria.
Granted my purchases are/were "Over the top " but it gave me a chance to learn first hand.
Both Eheim and Sunsun filters use thick walled PVC
tubing. The tubing is a bit more difficult to position but easy to get in place. It's easier than Fluval to drop tubing behind a tank that is inches from the wall. The thin wall poly from Fluval took more time and was frustrating.
The downside with Eheim tubing is that if it put in too tight of a radius, the tubing will kink and create a point of kinking in the future. Easily remedied by putting the tub in a piece of plumbing PVC
to accommodate any tight areas.
As far as media goes. Matrix or Eheim substrate will both work well. They are both sintered glass with high porosity. One may have higher porosity than the other, but the bacteria don't seem to care. I run both and even bought some of the Tyne Valley Aquatics Biohome ( see youtube, he's a POM ) sintered glass product with very high porosity.
On a side note he does have another youtube vid which shows how he recommends to pack his filter.
Hopefully this will help, or further fan the flames on the debate between Eheim and Fluvial.
Do look into the Sunsun. For $95.00 US i was pleasantly surprised, not bad for a cheap made in China, filter
As for Eheim, I personally like German engineering, and a simple design.
If you want, PM me and I will send you a pic of my tank and filter set up, for reference.
Now that my tanks are well filtered, I am learning the finer points of fertilizers for the planted part of the tank.
Any feedback on any of this is welcome.
There are some brilliant people on this forum.