I have an Eheim Classic 2217 running alongside my XP2. It has a noticeably higher flow rate and, in my opinion, filters better, as there is no way for the water going through it to bypass the media. It is slightly less convenient to clean than the XP2 but still fairly simple. Personally, I prefer the 2217, but they are both very good.
I have both filters outputting to spraybars running along the back of the tank and spraying towards the front, the 2217 output on the left and the XP2 on the right. I then have the 2217 intake on the bottom right corner of the tank and the XP2 intake on the bottom left. This setup ensures the water is circulating fairly evenly throughout the tank. I also have a Rena Smartheater on the intake of the XP2.
If you don't mind buying second hand, you can pick up a used 2217 for around £30-40.