This question is very subjective: even in Windows world there is no consensus right now on which antivirus is the best, and every antivirus is not immune to reporting false positives and missing out on some viruses. Clam AV for Linux is well known for that.
Truth is there is no best antivirus. The best antivirus is your own behavior - avoid visiting fishy websites and don't install non-legitimate software. That's your 80% security, in either world - Windows or Unix.
People don't realize a virus is software - and it doesn't jump onto your computer randomly, you as admin let it in. If you do, then you're screwed.
In the Linux world that seems to be fairly decent - people stick to official repositories more, install less of the external software. The biggest threat in the Linux world , and particularly for servers, are automated attacks by hackers, mostly on cracking passwords. For instance, my server on digital ocean constantly has tons of random IP addresses trying to brute force my root password. In such scenario, antiviruses are as useful as toilet paper.
If you do file sharing between Windows machines or Windows network shares and your system, then you may want to consider running antivirus. There are choices of Avast ,AVG, Kaspersky, Comodo, ClamAV.