Having owned both, here's a rundown of a few key areas based on my experiences.
Display
- The G3 has a higher resolution display, but LG rushed it to market. It looks a bit washed out and dull compared to most screens. Outdoor visibility can be difficult in direct sunlight. The G3's display is 5.5", but it feels a bit smaller due to the small bezels. It's still every bit of 5.5" though, which can be good or bad depending on the user.
- The S5 has a stellar 1080P display that has tremendous viewing angles and that gets super bright in direct sunlight. At 5.1", it's a solid size for most users.
Camera
- Outdoors and in good light, the S5 takes noticeably better pictures than the G3 to me. The G3 is no slouch, but the S5's shots have more detail, and its live HDR mode is fantastic.
- Indoors and in poor light without a flash, the G3 takes better pictures than the S5. The G3 has optical image stabilization (something the S5 lacks), which helps quite a bit. The S5 does a pretty good job in low light, but you often have to hold the phone still for a longer period of time (and your subject needs to remain still) in order to get a clear shot. With the flash on, the pictures from the S5 look a bit better to me.
Software
- Neither have the greatest skin, but the G3's is a bit lighter than the S5's. Each have their pros and cons, but much of it will come down to whether or not you like the features one offers over the other. Samsung goes into feature overkill with their software, but some of it is quite useful. The version of Android you'll get depends on your carrier, but most have a version of 5.0 at this time. Both tend to be equally slow with updates.
Other features
- The S5 has an IP67 rating against water and dust. Really comes in handy if you're caught in the rain or if you accidentally drop your phone in the water. Even if you baby your phone, it still provides great peace of mind. The G3 doesn't have any official IP rating.
- The S5 has a fingerprint scanner. It works well enough, but it's not as great as Touch ID on the iPhone or the scanner found in the S6. The G3 does not have a fingerprint scanner.
- The S5 has a heartrate monitor. The G3 does not have a fingerprint scanner.
- Removable battery & SD card slot - both phones allow you to change the battery and add a SD card.
Overall, while both are great phones, the S5 just has more to offer than the G3. It also gets more right than the G3 does. The G3 was a tremendous step in the right direction for LG, but they weren't able to fully realize that step until the G4. Between the S5 and the G3, my advice would be to go with the S5.
