What is the best brand in power banks for smartphones?

solar power bank /solar charger or waterproof poewr bank are best choice.
While no more words about how vital a power bank is for our mobile charging. And comparing with that, some buying tips seem to be more practical and useful.
Actually, here’re some basic guidelines on what kind power banks to buy. Surely, it, after all, depends on your individual needs and requrements.
If you have the habit of carrying too many devices while on travel, a high capacity power bank may be onto you; Of course, a low capacity portable charger would also be sufficient. Here are a few tips based on the major points:
Capacity: while choosing a right power bank, capacity is the foremost point you should consider. Power bank capacity refers to how much power is inside a power bank battery. Normally, it is measured in mAh or milliamps per hour. Noted that when charging a smart phone or tablet through a power bank, here will cause some power loss. So the real capacity of a power bank is about 70-75 percent of the battery capacity listed on the power bank. For example, a power bank with battery capacity at 10000mAh, while its real capacity may be in the range 7000mAh to 7500mAh. And this is for quality battery. If for downgraded battery, the loss of power is even more.
To meet ever-growing charging needs, many higher mAh units are available on the market now. But, keep your own usage in mind while wanna buy a power bank.
Connectors (or output ports): the number of connectors and the type of connectors matter. Regarding the type of connectors, Smart Charge and Quick Charge boost.
If you always forget to take along a charging cable, it would be more advisable to go for a power bank with built-in cable.
Smart Charge Features
Price: power banks with higher capacity while with a substantially lower price may not be genuine (Price of Best 20000mAh Power Bank). Pay attention, please. Most of them use refurbished battery which may not last long. Go for a power bank from a well known brand (Tips and Tricks: where to buy a reliable power bank), which, a bit expensive though, will keep your device safe.
Protective Circuitry: that will help you to better protect your device.
— Short Circuit Protection: to keep your power bank and the device safe when the short circuit problems happen.
— Over Charging Protection: to let the power bank cut off the power supply when your device is charged fully.
— Temperature Protection: to protect your device from overheating while charging.
Certification: DO check for the UL certification of the device, ensuring that the power bank you have been buying meets all standard quality requirements.
More you can check :

Here i listed 6 power bank i like most:
1. Anker 2nd Gen Astro Mini 3200mAh Power Bank: Anker was founded in 2009, the brainchild of a group of friends working at Google. Fast forward a few years and we’re now the industry leader in mobile power. Anker is the first power bank brand in North America. This Anker 3200mAh power bank is for your basic charging needs. It is very compact and helps you use your smartphone in critical situations when you need to make or take an important call and your smartphone has run out of battery juice. This 3200mAh external battery can charge your Apple iPhone 6 or iPhone 5S/5C more than once, the Nexus 5 once, the Samsung Galaxy S5 0.8 times, Galaxy Note 3 0.7 times, HTC One M8 0.9 times and the iPad mini 0.5 times.
2. Lepow U-Stone Series 12000mAh Power Bank: This Lepow Brand power bank– Red Dot Award Winner for its unique and timeless design, Faster recharging speed of 2.1A for a quick 7 hour charge (please use a 2.1A wall charger). Great energy conversion – higher than 85% for better efficiency, Biodegradable packaging made from recycled materials. U-Stone Package includes the Lepow U-Stone, Micro USB flat cable, and user manual. Apple adapters-30 pin, lightening and wall charger not included.
3. Jackery 6000mAh Power Bank:Jackery Brand mobile battery chargers go the distance. From sports fans to students, moms to mountain climbers, Jackery empowers people on the go. The power bank has single USB charging slot, and it assures full protection from any charging malfunctioning. There are four different colors to match your iPhone: Black, gold, orange, and silver while writing this. Jackery Bar is the smallest portable external battery with 2.1A output designed for extending mobile device battery life. It includes a high-energy density, fast-charging, compact design, and smart safety protection circuit. Jackery delivers beautiful design at affordable prices along with great customer service. The Jackery Bar is often used with leading smartphones and tablets like Samsung Galaxy, Apple iPhone, Apple iPad, and more. Jackery® Bar Performance for iPhones: 200%-300% battery life, Input: 5V/1A, Input charging time: 6-8h via Standard USB or AC adapter (not included); Output: 5V/2.1A; Compact Size: 3.8 x 1.8 x 0.9 inches; Weight: 5.5 ounce; 18- month warranty.
Buy on Amazon In US: Jackery 6000mAh Power Bank
4. Zendure A2 6000mAh Power Bank: Zendure USA Inc. was founded in 2013 by Tom Haflinger and Bryan Liu. The company’s mission is to deliver top-quality consumer electronics that exceed consumer expectations using high-end materials, premiere product development partners and user-centric design. The pocket-friendly A2 is our smallest portable charger, but with super-high-density battery cells, it’ll keep your phone charged long after the day is done. The Zendure A2 6000mAh external battery is highly durable, compact and lightweight. This power bank also has an auto-on feature which starts charging your device automatically after connecting it.
Buy on Amazon In USn: Zendure A2 6000mAh Power Bank
5. EasyAcc 10000mAh Power Bank: EasyAcc Accessory exists to please not to trouble. To make it easy as it uses and looks, The EasyAcc 10000mAh external battery is compact and ultra slim. It is attractive and is available in 6 different colors. This 10000 mAh portable charger is capable of charging the Samsung Galaxy S5 2.5 times, iPhone 5S 4.5 times, iPhone 6 nearly 4 times, iPad Air nearly once, HTC One M8, Moto X and Nexus 5 nearly 3 times, LG G3 and Sony Xperia Z3 more than 2 times.
Buy on Amazon In US: EasyAcc 10000mAh Power Bank
6. RAVPower 3rd Gen Deluxe 16750mAh Power Bank: RAVPower has made numerous powerbanks or external battery packs with each version improving upon the other.
One of the most important things about RAVPower is their reputation and reliability. The RAVPower 16750mAh portable charger is capable of charging various devices like AppleiPhone 6, iPhone 6 Plus, Apple 5S/5C, iPad Air mini, Samsung Galaxy S5, Galaxy S4, Galaxy Note 4, Galaxy Note 3, Galaxy Tab 4 Pro, Google Nexus, HTC One (M8), LG G3, MOTO X, Sony Xperia etc.