ESET Cyber Security Pro OR Bitdefender Antivirus??

My question;
Since August 2015 I'm using ESET Cyber Security Pro, and I'm pretty satisfied.
I really like the fact of it being an all-in-one solution (spam/malware/virus/firewall), that doesn't require me to install any additional software.
However, I realised that ESET Cyber Security Pro has a noticeable impact on system performance (specially using boot sequences).
- Now I ran into an antivirus review at macworld (although I'm not quite sure how reliable/independent this source is), and I started reading it.
In that review it's also clearly mentioned that ESET Cyber Security Pro (ranked #6 in their charts) has a noticeable impact on system performance... so luckily I'm not the only one noticing it.
Rank #1 is taken by Bitdefender Antivirus, which I find interesting. It's mentioned that Bitdefender scores pretty much 100% regarding security and that it has an impact on system performance hardly noticeable.
But... the thing that worries me a little bit, is the fact that Bitdefender Antivirus doesn't offer any firewall.

Now I would like to hear from you, if you would find it wise for me to switch from my current ESET Cyber Security Pro and move to Bitdefender Anivirus?
- And if your answer would be to indeed switch to Bitdefender Antivirus; what should I do to counter the loss of a firewall (that ESET does offer, and Bitdefender doesn't), would the default Gatekeeper be sufficient (or whatever the default security that Apple puts in its OS X might be named)... or should I indeed get myself an additional firewall?
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Relevant software and hardware I'm using;
OS X El Capitan 10.11.4
5K iMac released late 2015
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What I found and tried already;
macworld
I found out - as mentioned in the review above -, that ESET Cyber Security Pro has a noticeable impact on system performance, that I would like to get rid of if possible (who wouldn't?).
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