I prefer ESET, this is not an opinion just because I use ESET!
I've tried using Emsisoft more my system was slow, say Emsisoft does not weigh on the system, more me it did not, I do not know if it was just me ...
Use ESET ah nearly two months and never saw my system in a better state out, what but I liked was the technical support, are very attentive, it really surpeendeu me, meet me up at facebook, I find it incredible.
The default settings is enough for most users, more if you configure it, you get a much better performance, I have set it, and my system is clean as ever.
I would give a chance pro Emsisoft.
I repeat, my vote is to ESET as the Emsisoft did not do well with me, my system was too heavy.