"Good. We don't need no stinkin' Sprint." - John Legere
Even if they merge, they would still have be behind AT&T at #2.
Value: T-Mobile
Coverage: Verizon
You want unlocked phone with no carrier bloatware, buy either iPhone or Pixel from Verizon. The Pixel will have its bootloader locked but not many are into custom ROMs.
Then use it on Verizon if you prefer best coverage or best speed (from my experience) or go to T-Mobile to save money and get more data up to 50GB before throttle. TMo's customers are the most loyal.
Ignore AT&T and Sprint. T-Mobile's prices and Verizon's unlocked phones is why I can go back and forth with them both.
My history
Verizon: 1999-2001
Cingular/AT&T: 2001-2011
Sprint: 2004-2006
AT&T: Oct 2017- Feb 2017
Sprint: Feb 2017- Apr 2017
Verizon: Mar 2017-Sept 2017
T-Mobile: Mar 2017-Present
AT&T: 10 yrs, 4 months
Verizon: 2 yrs, 6 months
Sprint: 2 yrs, 2 months
T-Mobile: 7 months (don't include prepaid)
1. & 1A. Verizon or T-Mobile
3. AT&T
4. Sprint
Get your iPhones or Pixels from Verizon which lacks any carrier bloatware from them. Then either stay with them but pay up alot more or use those phones on T-Mobile which has the best unlimited plan at $70 flat rate. No taxes, hidden charges, service charges, etc.
I don't want T-Mobile to start raising prices. Legere needs to stay hungry, stay foolish.