Its certainly true that the store racks have all sorts of carabinersbig locking ones, cute little shaped carabiners with wire gates, D-shaped, oval-shaped (not so common today), different colors.
But really, its ultimately pretty simple. Any name-brand carabiner such as the ones you mention is going to be safe if used properly. Carabiners, ropes, and climbing harnesses are all extensively tested to meet standards approved by the European Union, the UIAA (the International Mountaineering and Climbing Federation), and other groups. Theyre also all rated to specific strengths defined in kilonewtons, which measure the force applied to a device as a function of weight, velocity, and gravity. You weigh 150 pounds, but when you fall and hit the end of the rope or anchor you exert kilonewtons, and that may be 10,000 pounds or more.
So heres a simple way to do this. For your climbing harness and your primary connection to rappel devices, belay devices, ropes, and everything else, use a big locking carabiner such as Omega Pacific Locking Standard D ($11; omegapac.com). This is a beefy carabiner with a locking gate so it cant be opened inadvertently. The Petzl Attache Screwgate ($13; en.petzl.com), and the Black Diamond Positron Screwgate ($11; bdel.com) work as well.
For all your slings and carabiners used for cams, stoppers, friend-type devices and the like, most any lightweight non-locking carabiner will work well. Black Diamonds Livewire ($9; bdel.com) has a wire gate and anodized aluminum body for light weight and strength. The Trango Superfly ($9; trango.com) or DMM Spectre ($11; dmmclimbing.com) are similar in design and strength. Im inclined to suggest you get ALL of one design or another, so they all feel the same in your hand.
The biggest safety issue of all, of course, is how you go about your climbing. If youre just starting out, connect with a group that offers competent instruction, such as the Mountaineers in Seattle. And always remember the words of that superb mountaineer Ed Viesturs: Getting to the top is optional. Getting down is mandatory.