I like avira

Eset Nod-32 & Kaspersky Both of them are the best ;)

Best Antivirus Engine
 

Kaspersky is one of the most reliable and complete antivirus software. It also gives the user the possibility to take decisions during the scanning process, but doesn't stop to wait for user input at every detection as antivira does (or did when I used it); this is a good thing. I used to have avira, but every scansion was a pain, it asked for a decision at every single detection.

Though Kaspersky is a resource eater, especially when its update process starts. Thus, in the end, I think nod32, which is much faster, is the best, even though is a little bit less secure than kaspersky (or seems so; I never reversed them, so far).

I went from Norton antivirus for DOS, to Dr. Solomons, and for quite some years been using Symantec Antivirus CE, and noways the new Symantec Endpoint Protection. Never let me down

Ahnlab V3 engine is g00d :)
contains patented technology and everyone knows the koreans are hard workers...

Nod Eset Smart Security.
Firewall & antivirus, 2 in 1.

Best is symantec endpoint portection -- it's a complete solution . Plus it does not take much resources.

Eset Nod32 best of the best

Comodo CIS with a manual tuning is a best.

G-data best

From Russia, with love.... The Kaspersky Anti-Virus Engine is of superior quality. I want to destroy speculation and rumors that the KAV engine is "slow". Scanning is clearly and measurably faster then most (if not all) of it's commercial counterparts. Scanning ONLY starts to suffer when the engine's security heuristics are moved to maximum levels due to so-called "hostile environments".

To me, detection/protection ability trumps speed 100% of the time so speed is not of a very great concern to me (especially since the move to multi-core CPU's and SSD's in almost all of my systems). Anyway, The "proactive defense" mechanism provided by these geniuses, is among the most stable and simple-to-understand that I have seen. The interface is very well-organized and intuitive versus some of the other bloated garbage being peddled out there.

Second to NONE unpacking capability. Kaspersky AV engine successfully unpacks more types of packing schemes then any other antivirus. I'm amazed. Of course, I do not use ANY antivirus on my systems as it is unnecessary for me. What i'm saying here is basically IF I DID HAVE TO CHOOSE one, then I'd go with Kaspersky products. And actually I DO for my clients. The SECRET to keeping everything trim and running super-fast is to ONLY install the AntiVirus & proactive defense components. All other components are absolutely UNNECESSARY BLOAT which are warranted only under extreme circumstances such as your client(s) being hard-core computer illiterates.

I can say much more about the engine but i think what i've said already will do nicely.

KAV is a death to old and slow computer, imho

#1 - Kaspersky Internet Security
Avira Premium Security Suite
NOD32 Smart Security

But i prefer to use avira .

Kaspersky of the eighth version.

I have used Symantec Corporate Edition for many years and now I have upgraded it to Symantec Endpoint Protection v11...
its centralized management is the best i've ever seen.