Don't believe the hype. There is no specific regulator design that is better for women. Still, that won't stop manufacturers from slapping some white and pink paint on the regulator and calling it "optimized for women." That's marketing BS...pure and simple.
For the most part, "smaller and lighter" refers to the topside characteristics of the reg. This is important to many people who travel to dive, considering that airlines are limiting the weight of carry-ons and charging for checked luggage.
Larger/heavier regs can also be neutrally buoyant in the water and theoretically just as "comfortable" underwater. This is managed by modulating the amount of air inside the second stage.
Some manufacturer marketing materials will lead consumers to believe that a smaller/lighter reg translates into less jaw fatigue. That's not necessarily the case. In my experience, I've found that one's choice of mouthpiece, hose length, and whether the reg is neutrally buoyant have more to do with eliciting jaw fatigue than the overall size of the reg. Many people consider the Sea-cure moldable mouthpiece and the Aqualung/Apeks Comfo-bite mouthpiece as two of the most comfortable mouthpieces on the market. FYI, you can mount these on any second stage regulator.
Something to keep in mind regarding regs is how the second stage routes exhaust bubbles. Some people prefer a wide exhaust tee for sending bubbles to the side of the face and out of the field of view. You really need to demo the reg underwater to evaluate this.
Regs will breathe differently due to design and how they are tuned. Some might feel more "mechanical" while others might feel more "natural." In the end, it should be about what you feel works best for you.
Most modern regs perform great when serviced properly and tuned correctly. Arguably, the most important factor which determines reg performance is the skill of the reg tech who last tuned it. Find a trustworthy, competent reg tech in your locale and make sure that you purchase a reg that he/she can work on. Scubapro makes great regs. Other manufacturers put out a quality product as well. You should also consider regs offered by Aqualung, Apeks, Zeagle, HOG, Mares, Atomic, Oceanic, and others. If you have a limited budget, shoot for something in the middle-of-the-line. Don't buy into the you-should-spend-as-much-as-you-can-on-a-reg-since-it's-life-support-equipment mentality. Also, understand that the regs that your instructor or DM is using might not be the best value for you. Dive pros get insider discounts that significantly skew the performance:value ratio. It is not unheard of for manufacturers to give dive pros as much as 60% off the MSRP on dive gear, since it's very effective advertising.
If you won't be diving in cold water (temps in 40s °F) and silty/contaminated water, then you probably won't need a sealed first stage. Once you narrow down your options, I'd recommend making another post to see whether SB participants like the various models you're considering. When possible, demo the reg underwater before purchasing it. There's no substitute for actually diving it. Hope this info helps...
