I use Avast.
I've used lots of stuff: Norton, Symantec, McAfee, Microsoft, Trend, BitDefender, AVG, Avira, and maybe some I don't recall.
I like Avast more than those.
They say Avast is one of the most problematic ones alongside with Kaspersky, Norton, McAfee etc... However, I've been happy with the free version of Avast, too. There's a couple of things you can do to tame it - or any other antivirus as well. It starts at the installation stage: Always do a custom install and disable all the features that you either don't need or that come with an extra price tag. In the case of Avast, the Minimal setup is where I start at, adding the browser shield and browser cleaner and potentially disabling the e-mail shield if no e-mail client program is being used. After major updates I go to Programs and Features in Windows, double click Avast, choose Modify and check if there's some new paid feature lurking.
When all is installed and good, I then go to the Settings and try to find every instance for Exceptions, browsing and adding C:\HitechCreations\* or aceshigh.exe where applicable, or the server IP addresses. That should minimise the negative impact of anti-virus checking every single package the game sends.
Bear in mind that no anti-xxx program is fool proof. Having one adds to the safety net, though, so using one is good practice.