I've had Sprint for about 3 years now and they've been fairly reliable. In the end, there is no 'best carrier. It all depends on where you live.
Word of advice... Don't get the Samsung 880 phone. It's small and has nice features but the call quality is *horrible* because it picks up so much background noise from the other side. Also, it plays through the speaker and headset about 50% of the time I use it. I'm on my 2nd phone and both did the exact same thing. I did some searching on those problems and found I'm not alone. I need to ditch this POS and pick another phone that's similar in size/features.
Word of advice... Don't get the Samsung 880 phone. It's small and has nice features but the call quality is *horrible* because it picks up so much background noise from the other side. Also, it plays through the speaker and headset about 50% of the time I use it. I'm on my 2nd phone and both did the exact same thing. I did some searching on those problems and found I'm not alone. I need to ditch this POS and pick another phone that's similar in size/features.