Don't listen to the folks telling you to use specific carriers. You're in Maylaysia, which means their suggestions likely aren't relevant over there.
As for the smartphones, the major operating systems are iOS, Android and Windows Phone. Each has similar features, and capabilities, and offers the ability to connect to any Windows computer.
iOS is run on iPhones. It's unique to Apple devices. And it's very good system. Primary negatives are that it is a closed system, and is unique to a single platform, but the popularity of the platform allows it to be a major player. It's also designed to be extremely intuitive...many of my clients complain it is not intuitive, because they're used to having to *use* their brains, and they try too hard.
Windows Phone is a relatively unpopular option with a tiny market share, but it does have a few benefits. The tiled interface is consistent with Windows 8, and integration is extremely simple. It is also designed to be very customizable. Beyond that, I've not used a Windows phone since switching over to Android.
Android is probably the most popular system out there. It uses an open software architecture that makes development simple, and runs on multiple platforms. Unlike the iPhone which provides a rich interface with little depth, Android provides depth but without the enforced consistency in the user interface.
For my use, Android is the superior system. It's almost *literally* like carrying a laptop around with me. Amazing devices, with an amazing OS. (Android is based on LINUX) But, in your position, I would look at both iPhone and Android systems.
As for the exact phone recommendation, Samsungs are amazing. But if you break the screen it is a very expensive repair...look at repair costs, as well, because those gigantic screens become increasingly fragile, and increasingly expensive, the larger they get. iPhone screens are laughably small, but comparatively inexpensive to replace.
HTC is another very good manufacturer, and so is Motorola.