What kind of flashlight do I need? Here are some considerations.

Bright enough or super-bright

Choose the correct level of light for the intended task. Too bright a light at night in a campsite or on a night walk will destroy your night-vision.
The brighter the light, the more battery power you will need.

Do you need an area light, close up to do chores? Do you need to see things far away?

A good floodlight will have a wide “spill” and not much of a center hotspot. You can see around you without moving the light much.
A spotlight will have a clearly defined hotspot and very little “spill”. To see an object on the side you have to move the light around.

Batteries come in several common sizes. From small to big, they are: coin-type (2016, 2032), AAA, AA, C, D, 9-volt. These are most commonly available as alkaline batteries.
Some of these sizes are available in the more expensive Lithium cell. They are coin-types, AAA, AA, C, D, CR2, and CR123A. Lithium batteries have a 10-year shelf life.
Larger batteries last much longer than smaller batteries.
Smaller batteries are used in smaller, more convenient sized lights.
Most of these battery sizes are available in a rechargeable form. They cost less to operate, but must be recharged frequently.

Large flashlights, such as C and D-cell lights, provide long lasting light, but are heavier and bigger.
Smaller lights using AA or AAA cells are lighter weight and more pocket-able, but provide a shorter battery life.
Coin cell lights are great for key chains, but are usually much dimmer.

Recent advances in LED lights have a built-in electronic regulator that keeps the light at full brightness even as the battery wears down. This provides a longer usable light life and a more efficient use of the batteries. When it finally dies, it dims fast but still provides a “moonlight” phase that allows you enough light to find and replace the batteries.
Because LED lights uses electronics, new ones often come with several levels of light. It can go from dim to medium to bright to flashing strobe just by pushing the switch; very useful in saving battery life until you need the bright setting.

Buy a LED flashlight. With ten times the battery life and being shockproof when dropped, there is no reason not to get one except that it costs more than the old-style flashlight.
With a LED flashlight, you don’t have to carry extra batteries or extra bulb.
For camping, get a medium bright light that has at least 10 hours or more battery life. A small 4-AA light with 3 LEDs has a battery life of 150 hours. That’s a MONTH of light if you use it only five hours a night.
For camping, consider getting a LED headlamp. This frees your hands to do things. Great for going to the bathroom at night and setting up tents in the dark.
For hiking, backpacking, camping and emergency use, see this link
For home and occasional use, you can get a brighter light because you would not be running it for long times. Again a LED flashlight makes more sense because you get both long battery life and an unbreakable LED bulb.