I own two eheim 2075, and they are top of the line filters. Recently i did an experiment with one of them, i took the impeller from a 2028 and put it on the 2075, the reason its the 2075 has 3 blades instead of six of the 2028, other then that its the same impeller. What i found the 2075 runs a bit more quiet then before and more flow.
Comparing 2075 and 2028, I like 2075 more because has 4 trays also 16 watts of electricity, and more flow, but its a bit more noisy then 2028.
Comparing with fx5, i don't think fluval can touch eheims for quality, design, reliability. I had a brand new fx5 and sold it 6 months later, i was doing micro bubles because of the polishing pads i was using sell by fluval,( blue ones) i hate to come home and work on my filters instead of enjoying the fish, or trying to figure was the problem with the filter. Media on the fx5 very limited my eheim 2028 holds more media then the fx5, to me me fx5 it just a big can with sponges that fows a lot water.
Read reviews about all the problems with fx5, i had to say again very please with all my eheim, one 2213, two 2217,two 2028,two 2075,one 2250, one 2260, and one 2262.