OMG, I thought I was the only one with multiple phones. Right now I'm switching between my iPhone 6+ and a new Moto x pure. I have a couple of windows phones, but the lack of apps (especially Verizon's messaging app) kills their use for me. I have both a Verizon and a Tmobile prepaid, so I use one phone with that account and my other with my Verizon account for my daily driver.
I have decided that going forward I will only buy phones that can be used on both Verizon and all other GSM carriers.
I have a lot of older phones that I don't use anymore and whoever said that you get nothing for them, you're right. I periodically donate them to a group that repurposes them for abused women. There is a drop off at my local Verizon store that I use.