Your question will get a lot of opinions based on personal experience/preference. So, in keeping with tradition, my recommendation is to consider using Malwarebytes
. The paid version, in addition to the usual features such as being resident and auto-updating malware signatures, also has a good IP blocker that prevents you stumbling across malicious websites, and also provides a flash scanning option which I find useful for removable media.
Having two anti-malware products is not neccesarily a bad thing : it depends entirely on the two products. In my case I have both MSE and Malwarebytes resident, and have never had any problems. You can also add ESET's services to Malwarebytes exclusion list, and probably vice-versa in the case of ESET, to prevent coflicts between the two.
If you do consider using Malwarebytes, take the time to post to their forum (accessible from their website) and ask about any incompatibility between ESET and Malwarebytes : they are very good at answering those questions.
Good luck with whatever choice you make.