What memory to go with

"What is the difference between these two latencies?" - Honestly, essentially none. The only way you would a difference between those two would be when you're running benchmarks. Even then, they'd have to be some really, REALLY sensitive benchmarks.

I'd used 4GB of budget DDR3-1333 CL9 in my rig before I took it out and replaced it with 8GB of DDR3-1600 CL8. What did I see? Well, I stuck the 1333 right back in alongside it because there was no NOTICEABLE difference whatsoever.

Ehem... anyway, back on topic. Your original choice is essentially a waste of money, UNLESS you are planning on doing some extreme overclocking.

Between the second two, the bottom is the better choice. Judging by your statement about looking for 1600mhz at 1.5v, I'm assuming you have a Sandybridge platform. Please, do correct me if I'm wrong. In that case, G.Skill's RipjawsX is your best option by far - Not only is G.Skill one of the most solid memory companies out there, the RipjawsX series was 'custom tailored' to the SB platform. I don't know whether or not there is a lot of difference, but it's a good thing to have on your side if something DOES go wrong and you need to talk to G.Skill about an RMA or the likes.

To sum that up in a single sentence: The top is overpriced overkill, the middle is great ram, but the bottom is also great ram which is advertised as being compatible with your platform.

 

Hope that all helps a little.