The Apple logo is pictured at a retail store in the Marina neighborhood in San Francisco, California
The Apple logo is pictured at a retail store in the Marina neighborhood in San Francisco, California April 23, 2014. REUTERS/Robert Galbraith Reuters

The countdown is on as the iPhone 6 and the bigger iPhone 6 Plus will become available on September 19 2014 and will start the rollout on select countries around the world.

For those lucky enough to experience ahead what the next iPhone is all about, as most markets will get the handset a little later in the year, it pays to use the days between now and Friday next week to mull over the essential details about the device before making the decision to buy.

4.7-inch or 5.5-inch screen

Market watchers are predicting that Apple will repeat history with the 5.5-inch iPhone 6 Plus. The consensus is the first iOS phablet will be a juggernaut that will dethrone the phablet originator from the top. In other words, Samsung's 5.7-inch Galaxy Note 4 is poised to take a serious beating in its epic battle with the supersized iPhone.

Yet for the average users, choosing between the smaller and bigger new iPhones is a matter of taste. Some would want to experience what Android fans have been harping about since the first Galaxy Note hit the market years ago so they'd go for the stretched screen profile.

Others or most would be happy with the 4.7-inch edition, which is a significant upgrade anyway from the 4-inch iPhone 5S. The display is relatively larger than before but easier to handle and move around with.

Also, pricing is a factor too as the iPhone phablet will have a premium price tag compared to the regular edition.

Storage offering

Gone are the days when 8GB and 16GB seem large enough, which is why Apple has significantly upsized the iPhone 6 internal memory options. The device in both models will come in 16GB, 64GB and 128GB configurations.

Again for most users, the basic 16GB model would seem suffice but over the days and months of extensive use that involves the capture of thousands of clips and images and downloads of movies and songs, that space will soon run out.

So to be safe, the choice is a toss between the 64GB and 128GB. The first should be spacious enough for many with extensive library of digital files while the latter will surely satisfy even the most obsessive hoarder.

Note, however, that the higher the gigabyte is the bigger the cash damage is.

Price tag

Per Apple, the larger iPhone 6 Plus price starts at $300 for the 16GB model with contract while the smaller variant is ready for take home at $200, also with lock-in agreement. Unlocked units begin at $650 for the 4.7-inch and $750 for the Plus edition. The tag can go as high as $950, which is for the 128GB jumbo make.

Contract-locked iPhones enjoy the benefit of assured network service plus some subsidies and for some carriers the bonus option of jumping into the next iPhone when it becomes available. For the SIM-free buyers, they'll have the luxury of hopping from one service provider to another at any given time plus the freedom of planning their usage.

But for those who believe the screen size don't matter but the price tag is, the iPhone 5S remains an excellent choice. The 5S in 16GB is available at a chopped off price of $100 or $150 for the 32GB model. Buyers who wish no contract hassles can instead get the open-line variants at one-off cost of $550 and $600 respectively.

Swap options

Millions of current iPhone users are set to upgrade and majority of them can and should capitalize on their existing units. Trade-in deals, online and through physical stores, abound out there but according to Business Insider, Amazon and eBay so far dangle the best prospects for swap hunters.

An iPhone 5S, which is in perfect working condition and the body free from dents and scruffs, can fetch appraisal values between $400 and $650, depending on model configuration and carrier/line status. Payments from these deals are either cash, gift cards or store credits that can be used to the purchase of a new iPhone 6.

Earlier iPhone editions are also accommodated but they normally attract lower cash/credit values.

So following the September 9 iPhone 6 introduction, buyers have 10 days to weigh in on the discussion above before the September 19 release date sets in.