I've owned 4 F18s in the last 4 years so I think I can comment well, I've never sailed a Cirrus or Falcon.
2009 Infusion: Sailed great but I felt for our heavy weight we were pushing the wide part of the hulls down a lot in the medium breeze range and slowing us down. Super light air it was never a problem.
Still the best boat I've sailed in big breeze downwind.
HUGE quality issues. Cracks in hull joint, airbombs in gelcoat, it was a chore to keep up with and not worth fixing all of it.
2011 Wildcat There were times where this boat was a blast to sail. It had some amazing modes upwind and downwind but we could only keep it in those modes about 60% of the time, kind of making it a one trick pony. Overall it was extremely hard to sail. Very hard to sail in light - medium air as it was hard to get back into a groove after a tack. It was difficult to sail in choppy conditions heavy conditions and we have always excelled in big conditions. We never had a problem in rolling waves in big wind. The hull quality seemed good but we heard some cracking noises that led me to believe there were interior issues, though this could have just been this boat. It comes with the oem best rope / hardware kit out of any f18 I've sailed, it's very ready to race from the factory.
We thought long and hard about going back to an infusion but there were a few things that kept me from doing so 1) track record with quality 2) track record with customer service in the US 3) I never liked the downhaul system, as it can't be truly continuous 4) medium air performance as I mentioned above.
The MKII does seem to have sorted out most of their quality issues and the new US distributor for Nacra does seem to be a bit more responsive (in my limited dealings with them).
So we ended up with a 2011 C2 and now we have a 2012. Overall this is my favorite boat so far (full disclosure I am a rep for AHPC). While the Wildcat had some amazing points upwind, the C2 feels to be the fastest upwind in all conditions. We've also never been so competitive downwind in light to medium air. I think does give up a little tiny bit to the infusion in big chop but this very minor in the big picture.
My only dislikes of the C2 are that there is a very occasional rear beam slap, we never had this on the infusion. The rudder system is great for buoys racing, very robust and little to go wrong. The Nacra style system is better for off the beach style distance racing, if that's what you're looking for.
I've also done a bit of sailing on Tigers and Capricorns several years ago. They are both excellent boats what for they are, entry level F18s. They both give up a bit in some conditions to the new F18s but can certainly still be competitive. Both are good quality with the Capricorns being a bit better. The Capricorn also has more of a more modern fit out more designed for buoys racing. The newer tigers had improved rigging.