Iphone 5s, SE, 6, 6s or 6Plus?

I'm looking at buying an iphone.

my requirements are as follows:

facetime,
64gb,
long term use,
economical

what are your suggestions?

It depends on your budget, but I would get an iPhone 6 Plus. It has everything you need, just if you drop it, your screen would probably break. I have an iPhone 6, but I wish I would've got the iPhone 6 Plus! It has a bigger screen and to me, it's faster and clearer!

If you get a 64GB iPhone 5s it will meet your specified requirements. Although the newer models will be faster but far more expensive. You can pick up a refurbished (near new) iPhone 5s 64GB for approx. £200 and get a sim only contract for £15-£20 per month. If you want economical this is your best option I think.

6s plus

If you're like me and don't like obnoxiously big sized phones - 5S and SE fits beautifully in the palms of your hands. That is, however because the 5S is already more than a couple years old, majority of apps 5 years later won't be delightfully fast; unless if you really don't care about speed.

iPhone 5S and SE are literally the same exact size, the iPhone SE is however the latest iPhone model & the 5S coming in at the oldest on your list. Both of these options would be very good if you're very low on the budget. So this is where we get into a Goldilocks scenario - would I want an older functioning iPhone at a mostly affording price? Or would I want a boost of lifespan with an ease of getting things done faster while reaching your thumbs easily on all corners of the screen without accessories? For this part, I'd wait a year or so until iPhone 7 and 7S (Plus) (or whatever they'll call it) until SE loses its value because it'll suck to run undesirable stability issues 5S would offer in 5 years.

THAT IS-If you don't care about size and need some more juice of battery and performance for lots of usage throughout the day - iPhone 6, or even more lethal, the 6S maxes-out all iPhone options of anyone's needs.

I hope I gave you some useful information while reading. I would also watch tech review related videos on YouTube which has to offer lots of very useful visual explanations of each iPhone's physical specifications.

My personal opinion: I would go with the iPhone SE until it loses a little of its value.