BrittO,
Since you have gotten the full Meridian perspective, I thought I'd offer some Kingsville thoughts.
I had heard nothing but bad things about the "atmosphere" at jet advanced. Hell, I put helos as my first choice! However, now that I'm through the program, I would have put jets first, second, and third. I really enjoyed my training here. The atmosphere is FAR better than primary.
First off, there is no "attrition is the mission" mentality here. The first impression I got when I started up was that the IPs (and 90% of the sim guys) was that they really wanted us to succeed. The idea that all jet guys are "screamers" and want to make your life miserable is BS. Sure, there are some bad apples here and there, but by and far the IPs, the command, and even the sim guys are top notch. I would take the worst sim guy here over the worst sim guy in primary ANY day.
You do have to watch your grades here. I never kept track of my grades in Primary until the week of selection, and I prided myself on not giving a damn. Why bother? Are you going to fly any better whether you know your grades or not? However, that bit me in the buttocks when I finished BIs and RIs below marginal at advanced. The good news is that if you DO keep track of your progress here and you need some help, all you have to do is ask. Class advisors, senior Marines, etc. will do what is necessary to help you succeed as long as you are making the effort and aren't a dirtbag.
All this boils down to being treated like a professional. My entire time here, I felt like I was treated with far more respect than was the case in primary. A lot more is expected of you, but you are treated better because of that. This may have more to do with the command than the pipeline. Which brings me to my final point. Choose Kingsville.
This is not a dig on Meridian guys. I think they produce just as good of pilots as K-Rock. It's not an issue of quality of training, pilots, or jets. From what I have heard and experienced, it seems that the quality of life is better here. I was convinced by a Meridian grad that I would be better off going to Kingsville. If you have additional requirements or priorities that make Meridian more attractive, go for it. But all things being equal, I think you will be much happier in Kingsville, especially if you are concerned about "atmosphere".
I have no first hand experience in Meridian, so feel free to chime in and correct me if I'm wrong.