I don't know...Well Eddie Brock's Venom is THE Venom, the one that brought the character to be one of Spider-Man's arch-enemies (ok ok...some of you will probably argue about this, but at the very least he is extremly popular) but that "we have to protect the innocents"...never liked it. On the other hand Mac Gargan....completely lacks any inhibitions Brock might have, has a cool design on his own, but...I only see him running around taking down lower class heroes in thunderbolts (if someone could tell me something I missed about Mac Gargan than was very ground breaking, I'm ok because I just knew what he did in Beyond! and in thunderbolts, so I might be wrong if I missed some of his appearances).
What I didn't like about Mac Gargan, is that in the last Thunderbolts issues, he has the typical "Eddie Brock" Venom face, and not his Venom appareance, you know with those "eyes within the eyes" stuff.
I don't know for you, but I'd really like to see a fight between Eddie Brock Venom and MacGargan Venom. Could be cool to show who the real Venom is (I don't know, by making that Mac Gargan's symbiote is just that clone from the Venom miniseries and that the real symbiote is on the loose...well it's still better than Norman Osborne sleeping with Gwen Stacy lol...), just kidding, it was just a stupid idea of mine, sorry