The LG G5 hasn't really lived up to expectations, and the price is up there. If that phone isn't doing it for you, but you have a hankering for a removable battery, the LG V10 might be the phone for you. It has similar hardware to the G4, but it's bigger with sturdier construction, and there's that second display. It's not usually a cheap phone, but the unlocked version is on sale today for $449.99 on eBay.
This is an unlocked GSM phone, so it'll work on carriers like AT&T and T-Mobile. Sprint and Verizon customers need not apply. The bands look great for AT&T and alright for T-Mobile. You'll only have 3G on Tmo in 1900MHz re-farmed areas, but you've got band 4 and 12 LTE. It has all of AT&T's main cellular bands.
The $450 price tag includes free shipping in the US, but there's no international option this time. Sorry. You'll only pay sales tax on this device in Florida.