1. Only the Verizon iPhone 6 has both CMDA and GSM radios enabled (most of the others only have GSM). So if you want an iPhone that will work with all the carrier networks, Verizon’s is the one you must get.
2. All Verizon LTE phones (i.e., iPhone 6) come factory unlocked due to FCC requirements on Verizon’s last LTE-band purchase. The others, usually not.
3. Half of the carriers (Verizon, Sprint, and some others) will not activate an unlocked phone that was not purchased through them (by checking for its serial number in their database). You can usually get around this by using the SIM card from another already activated (with the carrier) phone and plan, in the new phone.
4. The only way to purchase a full price iPhone 6 without a contract (though Verizon’s online store) is to purchase one with a somewhat hidden month-to-month $60 1GB plan.
Afterwards, when you receive the phone, this plan is never activated, or is canceled by you. You won’t get billed for it, and there is no cancellation fee (as it’s not a contract).
On the “Customize Your Plan & Add Accessories” step, where they want you to select an option in the “The MORE Everything Plan”, click the “View Single Line Plans” link…
5. To get Verizon’s $45 / month pre-paid plan, with no overages (e.g., the minutes and data just stop), buy Verizon’s “4G LTE SIM Activation Kit“. It costs $49.95 and comes with the first month included. And if you select to auto-pay, they double the data from 500MB to 1GB.
6. Don’t buy any of the cases, chargers, or other extra devices from the carrier. Their prices are double Amazon’s. And the selection of iPhone cases and accessories on Amazon is much nicer.
7. Get the Space Grey iPhone 6 Plus if you are indecisive on the color scheme.
While the “Gold” (Champagne) colored iPhone looks nice on the back, the white bezel on the front, around the black screen, does not have the same continuity with the black screen, breaking your thought process.
I hope this saves you the 4 days I spent (a.k.a. wasted) trying to navigate through the minefield of rules, plan prices, and incompatibilities, the phone companies enjoy putting people through to get the most money out of them.