NiMHs have a reasonably long lifespan and are widely available. Unfortunately, they do require electricity to recharge, meaning that it would be wise to take an extra set with you on a day out where you would use your camera a lot. On top of this, some cameras are not compatible with Nickel-metal hydride batteries, so it is important to check this before investing your money.
Another downside of NiMHs is that they have a high discharge rate (approximately 10-25% per month). This means that such batteries lose their energy quickly, even when they are not in use. This can be an inconvenience if you use your camera little and often.
Alkaline batteries are the most widely availablebatteries for cameras on the market at the moment. They have a large amount of energy and are very cheap to buy. However, most alkaline batteries simply cannot compete with other models in battery-intensive devices such as digital cameras which have a variety of functions.
Whereas alkaline batteries will enable you to take around 90 photos, lithium and NiMH batteries will easily reach 300 photos and beyond. Alkaline batteries are also non-toxic (since 1996 when mercury was banned from household batteries), meaning they can be simply thrown away.
Taking into account all the information regarding camera batteries and their lifespan, what you have to consider is how much you use your camera. If you use it on a regular basis, using lithium and rechargeable NiMH batteries would be the more suitable option as their lifespan can be good.
If you only use your camera for special occasions however, you should choose more carefully. Avoid using NiMHs as in the event of you needing them, you will probably find out that they are flat. Alkaline batteries have a longer lifespan than NiMHs when unused but a shorter lifespan than lithium batteries. However, alkaline batteries are much more eco-friendly compared with lithium batteries.
It could be said that the best way to equip yourself is to carry a variety of camera batteries with you that are both disposable and rechargeable. This will enable you to be as efficient as possible under different circumstances. The last thing you want to happen is for your camera to die at an important event or day out. In order to enable you to carry a range of batteries, there are special grips available from specialised shops which are very useful. These vertical grips attach to your camera and hold a series of spare batteries with you which will ensure that you never miss a shot.
It's a buyer's market out there and doing your research can allow you to be camera happy to your heart's content.