With Samsung dominating the market for Android smartphones, its rivals have had to get creative to compete.

Among those trying to stand apart from Samsung are Sony and LG, both of which recently released new flagship phones with fast processors, big screens and excellent battery life. Each offers a unique set of features.

LG's G Flex is the flashier of the two because it touts something truly different and immediately noticeable -- a curved screen. Unfortunately for LG, that screen is not only the phone's biggest attraction, but also its biggest weakness.

As you look at the G Flex's display, the curve is along the long edges of the phone. If you hold the phone like a landscape painting, the two sides are closer to you than the middle.

According to LG, the curved design has several benefits. It's supposed to give users a more immersive experience when watching videos. Because it mimics the shape of users' faces, the phone is able to place its microphone nearer their mouths and its speaker nearer their ears than other phones, allegedly improving the sound quality on calls. And it's supposed to make holding and interacting with the phone easier.

My take is that the curve is more of a marketing tool than a genuine benefit to customers. The curve does make holding and interacting with the phone somewhat easier than other devices with similarly large screens. But until we can start folding them in half, devices with 6-inch screens like the G Flex are by their nature going to be unwieldy to hold and use with one hand and difficult to wedge into a pocket, no matter what kind of curve they have.

In my tests, the G Flex sounded marginally better on calls than my iPhone or the Sony Xperia Z1S that I was also testing. But it still sounded tinny. Similarly, the wraparound screen made videos somewhat more immersive than on a typical smartphone, but was no substitute for a big-screen TV, or even a tablet.

And the screen has some notable shortcomings. Its resolution is relatively low compared with other high-end smartphones, so text is slightly fuzzy and videos can appear somewhat grainy. Additionally, the colors the screen displays noticeably shift as you view it from different angles. Whites in particular turn blue when viewed from the side.

The G Flex offers more than a curved screen, however. One thing I liked about the device was that LG has placed its power and volume control buttons on the back. That makes them much easier to access with one hand than if they were on the sides. The device also has a cool wake-up feature -- you can turn it on by simply double tapping anywhere on its screen. You can turn it off by doing the same thing.

Unfortunately, the G Flex also includes a whole slew of half-baked software features, few of which are useful or compelling. For example, the device has a feature that allows users to split the screen between two apps, which supposedly makes it easier to transfer information between them. But the space devoted to each app makes them hard to navigate or even view. And if you have to pull up the keyboard, it occludes nearly everything in both running applications.

Sony's Z1S is more subtle in its attempt to stand out from the pack. Unlike the G Flex, it looks like a standard smartphone -- a thin, flat, black slab.

But unlike most smartphones, the Z1S is waterproof. You can take it in the pool or lake with you down to about 4½ feet, assuming you've closed the protective flaps over its USB port and SIM card first. One cool thing you can do with the Z1S while it's submerged is take pictures; the phone has a physical camera button that you can use to launch its camera app while underwater.

Unfortunately, you can't really do anything else with the phone while it's submerged, because the water interferes with its touch screen. And if you're really into taking underwater photos, you probably want to go down much farther than 4½ feet.

The Z1S also tries to stand out through its camera and related apps. The camera has a 20-megapixel sensor, one of the largest and highest resolution on the market today. It's particular good at shooting low-light photos without a flash, although the colors appeared a bit off in my tests.

Like the camera apps on other phones, the one on the Z1S has multiple built-in features, such as the ability to record video and take panoramic shots. But unlike other phone makers, Sony has opened up the app so that users can plug new features into it. Instead of launching separate applications to take vintage-looking movies or add animated overlays to photos, users can plug such features directly into the main camera app and access them from there.

It's a good idea, and it will be interesting to see how many new features will eventually be compatible with the app. Right now, there are only 10, representing a tiny fraction of camera apps available for Android devices.

While its standout features aren't as flashy as those of the G Flex, the Z1S is a better device. It's smaller, easier to handle and has a much higher resolution screen. I like that LG is experimenting with a new design and a new style of display. But the Z1S, as pedestrian as it may look in comparison, feels a lot more practical.

Contact Troy Wolverton at 408-840-4285 or twolverton@mercurynews.com. Follow him at www.mercurynews.com/troy-wolverton or Twitter.com/troywolv.

6.5 out of 10
What: LG G Flex smartphone
Likes: Curved design unique, makes it easier to hold and use than other phones of similar size; rear buttons and "double tap" feature make it easy to turn on or adjust volume; extra long battery life; fast processor
Dislikes: Large, curved screen makes it difficult to fit in pocket or use with one hand compared to phones with smaller screens; screen is of relatively low resolution and its color shifts noticeably when viewed from different angles; many software features half-baked; camera performed poorly in low light
Specs: 2.26GHz quad-core processor; 6-inch, 1280 x 720 pixel screen; 2.1-megapixel front and 13-megapixel rear cameras
Price: $300 with two-year contract from AT&T or Sprint; $672 up front or $28 a month on two-year payment plan from T-Mobile
Web: www.lg.com


8.0 out of 10
What: Sony Xperia Z1S
smartphone
Likes: Sharp, high-resolution screen; fast processor; long battery life; camera that performs well in low-light situations; waterproof case; camera app that allows users to plug in new features
Dislikes: Only available from T-Mobile; only a handful of plug-ins are available for camera app
Specs: 2.2GHz quad-core processor; 5-inch, 1920 x 1080 pixel screen; 2-megapixel front and 20.7-megapixel rear cameras
Price: $600 up front or $25 a month on a two-year payment plan.
Web: www.sonymobile.com