Consumers are in for a treat in 2013 if the constant spate of rumors and leaks are to be believed. Several major players like Samsung, Apple, Google, and HTC are slated to unleash the next-generation of their best-selling smartphones, which will take the consumer market by storm.

We take a look at the top five upcoming smartphones to watch out for in 2013:

1. iPhone 6

Rumors surrounding Apple's next-gen iPhone offering are gathering momentum. The iPhone 6 is expected to sport a 5-inch Full HD display, possibly a Sharp IGZO (Indium Gallium Zinc Oxide) screen, and run on iOS 7. Speculations also point to a plastic chassis rather than a glass or unibody metal one.

Rumors also suggest that the iPhone 6 will step things up memory-wise as well and will also come in a 128GB avatar (in addition to 16/32/64GB). Despite the company touting its Passbook feature, Apple is also expected to pack in NFC, which was noticeably missing in the iPhone 5.

Release date: Rumored for Spring 2013/Mid-2013.

2. Samsung Galaxy S4

Smartphone market leader Samsung is expected to launch the follow-up to its best-selling Galaxy S3, dubbed the Galaxy S4. Although there is no official confirmation from the Korean company, a Samsung executive let slip the Galaxy S4 name at a press event back in 2012.

Word on the street is that Samsung will unveil the impending smartphone at the MWC 2013 in February this year. The Galaxy S4 is believed to feature a 4.99-inch 1080p AMOLED display, which could well be flexible and unbreakable.

Rumors suggest that the Galaxy S4 will likely feature a 13-megapixel primary camera, will be jus 9.1mm thick, and also have an S Pen stylus in tow. Moreover, the smartphone is also tipped to pack in the Exynos 5 Octa (8-core) processor and Android 5.0 Key Lime Pie.

Release date: Rumored for April/May 2013 release.

3. Samsung Galaxy Note 3

If rumors are to be believed, Samsung is also set to launch the successor to the Galaxy Note 2 phablet. If you thought the 5.5-inch Galaxy Note 2 was massive, wait till you set your sights on the Galaxy Note 3, which is expected to boast of a colossal 6.3-inch display, easily beating Huawei Ascend Mate, which is the biggest phablet in the market with 6.1-inch display.

That's right folks, the Galaxy Note 3 will apparently pack in a giant 6.3-inch HD display that will dwarf all the existing smartphone offerings. Considering Huawei's 6.1-inch Ascend Mate has shown us that 6-inch-plus phablets are possible, so the notion does not seem farfetched.

The Galaxy Note 3 is also expected to have the 8-core processor, clocked at 1.8GHz and the flexible display.

Release date: Rumored for Q3/Q4 2013 release. 

4. Nexus 5

Of late, rumors have been spreading like wildfire that LG is halting the production of its perennially sold out Nexus 4 smartphone. Rumor also has it that the company is working on the next iteration, the Nexus 5.

Per rumors, the Nexus 5 will sport a 5-inch display with Full HD (1920 x 1080 pixels resolution) and 440 ppi. NVIDIA Tegra 4 processor with 2GB of RAM is expected to power the device. The smartphone will pack in 8/16GB of on-board storage, a 13-megapixel primary camera, a 3-megapixel secondary camera, and Android 5.0 Key Lime Pie.

Release Date: Unknown, possibly late 2013.

5. HTC M7 

Taiwan-based HTC is slated to launch the HTC M7, its flagship phone for 2013 at the MWC 2013 in Barcelona. The HTC M7 is conjectured to have a 4.7-inch full HD display (1980 x 1080 pixels resolution) with 468ppi.

The HTC M7 is believed to deploy a SoLux display, which is superior to the Super LCD 2 panel found on the HTC One X and HTC One X+. The smartphone will also house a quad-core 1.7GHz processor, a 13-megapixel primary snapper, 2GB of RAM, 32GB of on-board storage, and a 2300mAh battery.

Release Date: Q1 2013.