Our top recommendation is GameSir's G3s, which strikes a good balance between price, performance, features, and build quality, making the G3s into a jack of all trades. If you're not looking to drop a ton on a controller, and you just want it to work—and work well—with your phone, the G3s is one of the best controllers out there for mobile platforms.
For an entry fee of just $30, you get a solidly-built plastic controller that, in addition to Android support, can also connect to a PS3 or PC over Bluetooth, making it a great backup controller for either of those systems. The controller supports both Bluetooth and an included 2.4GHz wireless adapter, so if your PC doesn't support Bluetooth, you can still use the device to control your Steam library. It also supports several different modes of communication between devices, included a mouse simulator, making the G3s a great choice for connecting to a home theater PC to use for media playback. On Android, you'll be connecting through standard Bluetooth 4.0, compared to some older controllers that only use Bluetooth 3.x to connect. The G3s has a 600mAh Li-poly battery that, according to GameSir, will last you 18 hours throughout normal use. The controller also supports a sleep mode for when the controller isn't in use, so if you forget to turn the controller off or it turns on in your bag, you'll be set to keep gaming once you get to your destination.
Let's talk about the control interface: it's solid, especially if you're coming from the PS3 or PS4 controller. The controller features twin thumbsticks set at the lower levels, similar to the Dualshock lineup from Sony. If you're coming from an Xbox or Nintendo controller, you'll have to get used to the difference in layout. On the upper left, you have a solid-feeling D-pad, useful for both platformers and fighting games alike. On the upper right, a standard XYBA button layout that makes the controller feel like a combination between the Dualshock 4 and Xbox One controllers. Each of these four face buttons have a backlight for playing in the dark. The controller supports vibration, with motors built into the bottom ends of the controller. In the middle face of the controller, you'll find standard Select and Start buttons, as well as a "Clear" button and a button to enable or disable "Turbo" mode, which lets you continue to shoot weapons in FPS games by holding the trigger down. On the top of the controller, you'll find the standard shoulder buttons and triggers, which look and feel similar to those of the Dualshock 4.
One major problem with a lot of Android controllers is the compromise between standard shapes and styles and allowing room for a clip to hold your smartphone. Many controllers with built-in clips will sacrifice ergonomics and design to be able to support a phone mount, while the better-designed and better-feeling controllers require you to prop or hold your phone, making it next-to-impossible to play on a bus or subway. The G3s makes room for a compromise between the two, but it does so at a premium cost. The standard controller comes without a mount, and purchasing the standard clip-on mount for the G3s costs an extra $13 on top of the $30 base controller. While it's a bit pricey for what amounts to a piece of shaped metal-and-plastic, the mount works well, doesn't weigh down the device, and is easy to take on and off as needed. It doesn't take up too much room, and can be easily discarded of when not in use. The nature of the clip means you don't have to pay extra if you aren't going to use it, and it doesn't mess with the design of the device in the slightest.
Of course, a controller would be nothing if it didn't work well with your phone or tablet. Lucky enough, the G3s is a great controller, both on Android devices and PCs alike. The rechargeable battery makes it easy to keep playing for days at a time, and there aren't any major connection issues between the devices. The different modes make it easy to switch between standard game controls and mouse controls, as well as staying paired between multiple devices at once. And the matte plastic keeps up appearances, even after hours of gaming.
Overall, the G3s is exactly what we like to see in a gaming controller. It's not too expensive, it can support phone clips for holding your phone up while gaming, and it feels good in the hand. There are nicer controllers in all three categories that we'll mention later on this list, but the G3s is the only one that can strike a balance between these categories, and that's what makes the product our top pick. It's good for nearly every use case we can think of, and it'll make most consumers satisfied for all of their gaming needs.