I'm going to start by saying that my experience is very limited, so take absolutely everything I say with a grain of salt.
However, I do love the challenge of 500 point lists, and I don't see many posted, so I'm going to chime in.
Personally I would tend towards your second list for the following reasons:
1: at 500 points you're not going to be seeing an enormous amount of enemy armour, so 6dl shots per turn may end up (assuming you're lucky with dice) being soaked into infantry.
2: a haemonculus without a liquifier is basically two ten point wracks and a thirty point pain token that gives away a victory point when it's killed in cc. I'm not convinced.. Better to hide it on a boat and drop templates.
3: if you're deploying outside of transports, list two gives you an extra units worth of target saturation first turn, you never know how useful that might be..
That said, I've been experimenting with 500pt combos recently, and there are a couple less commonplace ideas to play around with that I'm beginning to think could be particularly effective as they tackle some of our fragility issues. They work especially well if you're playing on a 4x4 rather than a 6x4 board.
First, I would consider a talos, rather than a ravager. It's a hell of a lot more durable (and smaller, so easier to hide), and so will pull fire away from your troops for longer. On a smaller board its lack of speed is less of an issue, and with luck it can offer short range AP1 (liquifier) and melee ST10 AP2 (smash). Plus, once the vehicles are gone, it can happily terrorize infantry and characters, something that ravagers are less good at. The sacrifice in T1 AT is admittedly painful, but I'm not convinced it's a list breaker..
Secondly, Beasts. And I may get dragged over the coals for this, but a single beastmaster with two razorwing flocks is 42 points. It has 11 wounds. It's a massive draw for st6 and above fire (but consequently may get instagibbed), and in cc has the potential to threaten light tanks with rending attacks. Sure, it may not be the most durable unit if a whole bunch of heavy fire is pointed at it, but it can go to ground, its small, so can hug cover, and its 42 points for 11 wounds and 11cc attacks! Three wracks are 30 points for 3W and 3A. How is that not a bargain? And again, even better for a small board. The only major downside i can see is the sacrifice of a potential venom, but I'm beginning to think it might be worth it..
This is all highly speculative, but hopefully it's food for thought..