You have 3 Good filters listed.
Ehiem 2262 will hold I believe 18L of media and will have roughly the same flow rate as the Fx5 which will be around 500-700 GPH. The Fx5 has a 600 GPH filter flow rate. Don't be fooled by the 900GPH marketing scam.
The Eheim 2080 will have a flow rate less than 350 GPH and hold 12 liters of media.
The Fx5 holds the least amount of media topping at almost 6 liters with a 600 GPH flow rate.
If you have the money, go with the Eheim 2262.
The Eheim 2080 is very good at bio filtration. In fact Both Eheims will kill the Fx5 at bio filtration because of a few things. Contact time with the media, water velocity through the media and the amount of media.
The Fx5 will less contact time, higher velocity and less media than the other Eheims listed
Now if you want good mechanical filtration, I would go with one of the three filters with higher flow rates. The Fx5 does a great job, however, using small partical filtration pads or filter fiber will clog up usually within a month. The 2262 will not have this issue.
The Fx5 is able to be modified though. After modification you can make it hold roughly 10-12 liters of media instead of just over 5. You will increase the cross sectional surface area for small partical filtration meaning it will not clog nearly as fast, you will also slow down water velocty through the media and increase media contact time. All of which are very good.
Internal Mod
HERE
There is a new small mod to the Fx5 which could work in conjunction with the mod spoken about above. This particular mod could solve the purging issue that you have after the modification IF you do not modifiy the cover correctly. The link above will show you how I did it but failed early because I did not use the correct adheasive. It did work 100% though and very quickly.
This purging mod can be found
HERE
So its up to you. If you are a DIYer and wouldn't mind spending a little extra $$ on some small things to modify the Fx5, then I would go that route. However if you have the money and want a high flow rate and lots of media, go with the 2262.