I applaud your desire to buy your own gear! It increases the likelihood that you and your wife will dive more, which increases the likelihood that you will become more proficient, which increase the likelihood that you will come to appreciate the subtle differences , in inherent buoyancy, lift, and functionality that can ultimately be discerned among BCDs.
kenji:
Our LDS generally recommends Scubapro, Cressi and Zeagle for BCs.
So, I presume that the brands that your LDS carries are Scubapro, Cressi and Zeagle, as opposed to Halcyon, Aqualung, Apeks, Dive Rite, etc. Nothing wrong with that – just be aware that any shop can be expected to be one that ‘generally recommends’ whatever brands its carries. All of the brands that you LDS mention are good – nothing wrong with their products. All of the models that you mention are good products. Personally, I would not buy any of them,
today (I emphasize that even though my first BCD was a Zeagle Ranger). But, that is just my view.
For now, any of the BCDs you mention will serve you equally ‘well’. (Or, I guess, equally poorly.) Trying to find one BCD that will perform equally well in warm tropical waters, AND colder northern waters, AND be so light that you can pack your suitcases with lots of non-dive clothes, etc. when you travel, is a challenging task, which few BCDs do well. So, you will find that whatever BCD you pick may not meet
all of your needs. Maybe, you need to decide which of those criteria is the most important, and base your choice on that. Or, look at the cheapest, and just pick that one.
Frankly, you can flip a coin, and come up with a reasonable choice. Or, put the names ‘Cressi Ace’, ‘Zeagle Ranger’, and ‘ScubaPro Knighthawk’ on slips of paper, put them in a hat and pick one. Really. I am serious, and I do not mean the comment to be sarcastic or cynical. And, either approach (coin or slips of paper) is probably a more functional approach than driving yourself crazy with questions (and, by inference, your LDS staff as well). Years ago, I was at a point where I could not decide what brand of PC (Dell, IBM, or Gateway in that case). I had experience with all 3 brands. I literally picked a slip of paper out of a hat, and ended up with a Gateway. I have never questioned that approach. I subsequently owned multiple Dells, and IBMs and Lenovos, and can say with reasonable certainty that my early obsession over making the one and only one ‘right’ choice was needless and 'for naught.‘
From my perspective all of the BCDs you mention ‘suffer’ from the same inherent design flaws – 1) suboptimal placement of primary weight pockets relative to a) the body’s physiologic center of lift, and b) the body’s coronal plane (lateral, vertical midline), 2) needless inherent positive buoyancy, and 3) excess lift, particularly in the larger sizes, relative to what most divers ever need. But, these flaws are something that few scuba enthusiasts ever notice, because they are so focused on other things (their gas supply, their dive time, etc.).
None of the manufacturers of these BCDs provide you with a particularly useful piece of information - the inherent buoyancy of the particular scuba unit. Most of these units are (very) positively buoyant, which mean you need to wear extra weight simply to compensate for the (needless) inherent positive buoyancy of the BCD. That makes a great deal of difference to me. It may not be noticeable to you.
Depending on your size – assuming you are going to require at least a medium and probably a large size in any of the units - you will probably end up with far more lift than you need for diving in warmer waters (presumably the basis for your question about travel). For example, the Knighthawk provides 46 lbs of lift, and 34 lbs in the S size. The Cressi Ace provides 43 lbs in the Medium, and 51 lbs in the Large and X-Large sizes. I never use more than 30 lbs for single cylinder diving, and sometimes as little as 18 lbs. In fact, I never use more than 55 lbs for diving double steel cylinders.
kenji:
I guess I just want others opinions
So, here's an opinion: Buy a BCD, one for you and one for your wife. Pick
any of the models you are thinking about. Use the BCDs to dive – move that number which is now in the teens, to the triple digits. Which BCD you use to get there is less important than using the journey to find out how to optimize
your weight, and trim, and breathing, and finning, and dive planning, and . . .
As for opinions about specific 'best' gear, all that any of us can do is tell you what WE use, and why - NOT what is best for you. I happen to use a stainless steel backplate and wing, for diving in cold water, for diving in our NC coastal waters, for diving in warm Caribbean water, and for traveling between the various locales. I have my particular reasons for that choice, and it reflects my accumulated experience over 1000+ dives. What I do, or choose, may or may not be applicable to your situation. But, that configuration works for me.
The Knighthawk seems to have one of the best reputations out there, but it is heavier for travel. 
