We didn't run full battery tests; we concentrated on two key areas instead - web browsing and video playback. The Galaxy R has an extra 150mAh of battery capacity, but we had to see if the Optimus 2X could make up for it with higher power efficiency, mainly due to the smaller screen.
We conducted our usual web browsing test - the phones connect over Wi-Fi, with the screen set at 50% brightness and we have them open an automated test page that loads various real-life web pages (local copies, to avoid third-party server issues).
Surprisingly, the two phones ran out of juice within 15 minutes of each other. The LG Optimus 2X lasted 4 hours and 54 minutes, while the Samsung Galaxy R barely outdid it with 5 hours and 7 minutes.
We charged both phones back up and fired their video players. We made sure we put them in Airplane mode to avoid network connection issues affecting the battery results. We ran the test until both hit 10% reaming charge, which is where most phones stop their media players.
This time the Galaxy R enjoyed a more decisive victory - it lasted a full hour longer than the Optimus 2X. It was 5 hours and 20 minutes before the Optimus 2X called it quits, while the Galaxy R went on for 6 hours and 21 minutes.
Both phones were in the middle of the pack in terms of battery life and either one of them can help you kill time for five hours straight. But for people who like to catch up with their favorite shows or watch a movie on the go, the Samsung Galaxy R can give you an extra hour despite its bigger, brighter screen.
The LG Optimus 2X was a flagship in its heyday while the Samsung I9103 Galaxy R was simply meant as a more affordable version of the Galaxy S II. Nearly half a year sets the two apart, but they demonstrated very similar performance in our quick shootout.
The biggest differentiating factor between the two seems to be TV-Out - if you want to pair your phone with the TV, the LG Optimus 2X offers FullHD playback over HDMI with mirroring, whereas the Galaxy R has only the wireless DLNA option (also available on the 2X).
Other than that, the Optimus 2X has the better camera, but not by as much as the numbers suggest (8MP vs. 5MP, 1080p vs. 720p). The 10% bigger screen of the Galaxy R is much brighter than the 2X's display, but you'll have to settle for poorer black levels.
The tradeoffs go on - if you want to watch videos on the go, the Samsung phone offers a full hour more of battery life, but if you browse more than you watch video, then the LG will probably offer a smoother experience due to its better performance.
Then there are the subjective differences like styling, custom Android UIs and so on. These are matters of personal taste and we shouldn't be telling you which one is better.
It all boils down to what you use your mobile phone for. Any of the phones in this comparison would be more than happy to serve. And although the LG Optimus 2X clearly has the upper hand in imaging and connectivity, the bottom line is that both phones are hard to beat for their performance to price.