With the LED, how much does a suitable driver cost? This sometimes is also forgotten, along with shipping/handling.... and AVAILABILITY!
For an emergency backup light when you loose power, ceiling bounce a flashlight. Find a flashlight/battery combo that gives you the runtime that you need.
Efficiency is for you to test. Most 'marketing types' are grossly overrating the LED bulbs on the market by not including the 'power wasted' by the driver/ballast/powersupply.... and light lost through lens/optics/..... It'll take 1.2w to get that 120lm from that 1w 140lm/w LED. As you can see, numbers can be manipulated by leaving out the power lost to the driver, and lumen output lost through the optics.
You can't go wrong with ANY of the name brand LEDs. The choice is yours. Parameters are needed.
A 12v bridgelux can connect straight to a 12v battery. A 3.3v Cree will need a power wasting voltage step down buck driver to use the same battery. Which is better now?
A 3.3v Cree can be driven directly off of 3xAAA batteries. But, that 12v Bridgelux will need that step up boost driver. Which is better now?
Your Cree, Nichia, Luxeon, Seoul, Luminus, Bridgelux, Citizen, Sharp, LedEngin, Edison, Osram, Stanley, .... LEDs all have their pros and cons. I wouldn't simply jump on one saying its the 'cheapest' or 'most efficient' because it depends on the parameters.
Do you want flood or spot? how bright does it need to be? How many LEDs do you want to use? What is the budget? What type of battery power is available, and its chargers? Do you want warm, neutral, cool LEDs? Is CRI important?
What are you willing to sacrifice for cheap?
What are you willing to sacrifice for efficient?
XML-U2 cool, might tolerate it as a never used glovebox flashlight. I wouldn't want it lighting my room since I demand less tiring, on my old eyes, the neutral to warm LEDs, preferably 80CRI or higher.