I have a half dozen SureFires, from an M3 to the E2e, a Scorpion, a rechargeable SL20XP, and a Petzl LED.
The SureFires are essentially overbuilt, hard use "tactical" lights that represent the best production flashlights - durable, bright, nice features, etc, but they are expensive and their rechargeables are less convenient. If you don't really need SF features, there are cheaper lights that work just as well - but aren't built like tanks. For your intended use, the E2/E2e, G2, or 6P lights, or the rechargeable 8NX, are all good choices.
The SL Scorpion is a great light, and for walking the dog it would be a great choice. If you anticipate using it a lot, the 123 batteries are expensive, but the light itself is a great value. Can't go wrong here, this is a super bright, durable and affordable light. Unless you run over it with your car, you might never know it's not a SureFire, although it lacks the lockout tailcap.
The SL Poly Stinger rechargeable is an excellent solution for a frequently used utility light - it's compact, durable, has a convenient recharger, and it's bright. It's not a "tactical" light, but it's a first class utility flashlight and you won't be buying $10 worth of batteries every two weeks.
The LED lights are cool -they're also VERY easy on batteries. If you need light 20ft away though, there are better choices. The LED's are terrific for illuminating your immediate surroundings for long periods, and they ration power wisely. No problem seeing them from a long way off, and you won't blind anybody.
Bottom line? Put a Petzl Tikka LED on your dogs collar, get a Streamlight Polystinger for general use around the house and walking the dog, and a SureFire E2e or 6P - or a Scorpion if you don't want to pay for the SF lockout cap and enhanced durability - for an EDC backup light.