Whether you're a champion bicyclist or a novice going for a spin around the park, you need to keep your tyres
Some pumps are small enough to fit in your purse, the pouch in your car seat or even your back pocket. Others can be attached to your bike frame so you'll always have them while riding. Being able to access and travel with your bike pump is useful, but the pumps themselves are not the most efficient. Because their small and hand-operated, you'll likely be pumping for a very long time before you see results--it can be quite a workout. Regular-sized floor pumps, on the other hand, require far less effort and can pump a tire fully in approximately a minute.
Some mini-pumps have a lot of moving parts that you often need to unfold and click into place. All the small, moving pieces increase the possibility of breaking something. Full size pumps are often more durable because they are not tailored for portability, thus the materials they're made out of are heavier--various metals--and they have less moving parts. Also, since you aren't likely to need a ton of force or vigorous motion while pumping, they're even more likely to stand the test of time.
The following is list of reputable bike pump manufacturers. Look for products put out by these companies to ensure that you're getting something of quality.