Personally, I love both, but I've only owned 92's. Many people find the grips too chubby and think the safety is in an awkward place, which are 100% valid complaints.
Aside from a preference of ergonomics, I think there is a lot of FUD surrounding the 92 resulting from some early design problems that got worked out a long time ago. See here:
http://www.sightm1911.com/lib/history/true_story_m9.htm
That said, if I were going to pick an option for someone who needed a pistol for defensive use, I'd choose the 75. The ergonomics are better, and the ability to carry with the hammer cocked and the safety on is a nice compromise between readiness and safety. However, if I wanted to err on the side of safety, I'd choose the 92. Less potential for "oopsies" due to the heavy DA pull and the presence of a dual safety/de-cocker mechanism (with the 75, you pick one or the other). I am also much more accurate with the 92, but that could just be practice.
Though my Beretta's role is solely sport, it
can be a good defensive pistol but (IMO) requires some modification and knowledge of the platform. Common mods include installation of a short-reach trigger to mitigate the issue of the fat grip and installing a lighter hammer spring for an easier DA pull (the stock one is HEAVY...20lbs). Wilson combat also offers a one-sided safety to reduce the chance of accidental engagement while racking the slide.
If you're going to go with the Beretta, I highly recommend getting a Vertec (if you can find one) or the M9A3 (if Beretta has come to their senses and priced it reasonably). These feature straight, 1911 style grips and removable front sights. The M9A3 also accommodates quick-change grips and an over-center safety lever to reduce the chance of accidental safety engagement.
Also, one more thing that may or may not make a difference to you. Beretta customer service can be spotty; if something goes wrong, you're paying to send it in, and the repair may not be quick. On the bright side, on this particular Beretta product, there isn't a whole heck of a lot to break past easily replaceable, consumable parts (e.g., recoil spring), so you'll probably never need to make use of their repair services.