The iPhone has always had reasonable battery life, but as the power of the chip inside as increased, Apple has struggled to keep endurance from falling behind. The small, thin iPhone 5 only has so much room, and a small battery almost always leads to modest talk time.

Buying a battery case is the easy solution. But which should you buy? There are numerous options available for the iPhone 5, and all of them basically do the same thing: add battery life. Yet some manage to gain an edge over the competition through size, design or endurance.

Here’s the best of the best.

iBattz Mojo Power Bank ($79)

In a test by Laptop Magazine the iBattz Mojo Hi5 Power Bank beat the endurance of the next-closest competitor by almost three hours. That gap is larger than the gap between the four cases combined, making the Hi5 Power Bank a clear choice for anyone who seeks maximum endurance. Better still, this case is priced at just $79, which is less than many competitors with much smaller batteries.

These benefits are balanced by the Hi5’s heft and size. The massive 2500mAh battery is housed in a case that’s 18.2mm thick also weighs in at a whopping 18.8 grams. The battery is detachable, however, so you don’t have to carry its weight when not needed.

Lenmar Meridian ($89)

The Lenmar took second-best in the aforemention Laptop Magazine round-up the Hi5 Power Bank dominated, almost doubling the iPhone 5’s default battery life with its 2300mAh battery. That’s incredible considering the Lenmar’s 15mm thin profile. It’s rare for a battery case to offer excellent endurance and add minimal bulk.

On the downside…well, there isn’t a downside. The Meridian looks good, is well built, offers a LED power indicator and on/off switch for the battery, and can be had in three colors. The only problem, if you can consider it such, is the $89 price tag. That’s towards the high end of the market, though you certainly get what you pay for.

Maxboost Fusion [No Longer Available] ($69) / Atomic Plus ($79)

Maxboost cases are popular on Amazon. This probably has a lot to do with their price, which starts at $69 for the Fusion and $79 for the Atomic. These cases offer 2000mAh and 3000mAh batteries, respectively, so you’re getting a lot of capacity for your dollar. Buyers also seem to enjoy the plethora of color options. While most competitors have one or two choices, the Fusion offers twenty.

The cases otherwise offer typical features and, despite their capacities, are not particularly thick (15.5mm for the Fusion and 18mm for the Atomic). All of Maxboost’s cases receive favorable reviews on Amazon. There are no published professional reviews of the company’s products, however, and the corporate website is full of grammar issues. These facts may raise eyebrows from buyers concerned about support and long-term quality.

Mophie Juice Pack ($79 and up)

The capacity-per-dollar value of these products may appear poor, but reviews indicate that Mophie products punch above their weight, putting the 1500mAh Helium case almost on par with 2000mAh cases from other companies. With that said, however, the $79 Helium doesn’t last as long as many cases available for the same price.

Design is the real selling point for Mophie products. Reviews across the web praise these cases for their attractive looks, thin profile, easy attachment and attention to detail. The Helium is perfect for iPhone users who want more battery life but also want to add as little bulk as possible.

MyCharge Freedom ($79)

Those looking for an elegant, durable case should consider the MyCharge Freedom. Unlike most competitors, this case features a metal outer case which looks great and, combined with a rubber interior, provides excellent all-around protection.

Inside the Freedom’s 15.5mm thick case is a 2000mAh battery which can power the iPhone 5 for nine hours. This result is better than the Helium, but behind the Lenmar Meridian and way behind the iBattz Hi5 Power Bank. Another boon is a relatively open and accessible bottom which allows for easy connection headphones or the charging cable.

Buyers must drop $79 for the Freedom, which is on par with competitors that offer similar battery life.

Conclusion

Picking a winner from this group is difficult. Most of the packs fall between $69 and $89 and most offer similar performance. There is, however, one case that stands out from the rest; the Lenmar Meridian.

What makes the Meridian great is its combination of performance and design. Offering ten hours of endurance, this case beats the majority of competitors, yet is also among the slimmest on this list. That’s a hard combination to beat, and while the $89 price tag is a bit expensive, it’s only $10 more than average.

Do you own an iPhone battery case? Let us know what you think about it in the comments.