I would actually lean towards Roma with the card actions or a more thematic Battle Line. It's pretty unique though with the area control mechanic and the Locations that have abilities as well.
Is there a lot of murdering and take that and ruining everything for the other side?
It's a competitive game so there is some direct conflict. I wouldn't call it overly aggressive and since both players have the exact same deck the game is fairly balanced. As balanced as a card game with card draws can be I suppose. The conflict comes in the form of taking Trinkets & Potions from the other player as well as removing their player markers from the Locations. I love the game but I also think Arena is great as well, so your mileage may vary.
Hemloch is lighter than Omen, so it will be easier to get a light-gamer into the game. I think overall Omen has more options for tactical play, but you won't be on a strategic autopilot with Hemloch like you might be with some of the other games you mentioned.
There is a fair amount of "take that" play, mostly from the threat of minion stealing and the elimination of influence markers from key spots on the location cards. But it's not the kind of game that's really going to get under your skin when someone wrecks you plans -- mainly because it's a quick game. Experienced players can play in 15-20 minutes after the draft is complete. Speaking of draft, that's one area that Hemloch an Omen both shine above some of the other games you listed. Once you've played several times and are very familiar with the cards, the Draft Variant really shines and brings in a new dimension of strategy.
The game certainly isn't for everyone, but I'd highly recommend it to anyone looking for a quick and portable 2-player game that can enjoyed by both casual and experienced gamers.