Originally Posted by
scubadu
Honestly, at this point, I'm not even sure what you are asking from this forum. Your choices are pretty clear and all them cost you money; only you can decide how much you are willing to spend in order to accomplish your desired use case. Nobody here can decide that for you.
^^
1. If you decide to buy new phone, get it from apple directly. That way guaranteed factory unlocked - although Vz sells theirs factory unlocked, others don't automatically. The most versatile iphones with max bandwidth coverages are either the Vz or ATT model.
2. If you go with 6s, get at least 64 gb, whatever you do, don't buy the 16gb models.
3. Used and unlocked iPhone 5, 5s, even 4s are available for very reasonable prices. 4s can be had for $100 or less depending on condition, 5s under $250. If you buy from eBay, make sure seller has perfect 100% rating and is a private rather than mass seller. I've bought and sold BB, iPhones for friends and families on both eBay and CL without ever a problem.
Good luck!