Default [Q]best carrier to use with unlocked phones?

I'm rocking a unlocked Nexus 5, using a straight talk T-Mo Sim, $45 unlimited. I'm not liking straight talk for a particular reason. I'm paying for unlimited data up to 3Gb. After I go over the 3Gb they throttle. Which is fine. What isn't fine, is how much they throttle my service. I go from about 6Gbps, to 30Kbps after I go over. It's stupid slow. This isn't unlimited data in my book. I don't care about getting throttled, but that is to slow.

What carrier can I go to, that won't do this to me? Any, don't care about the price. Just something unlimited, that won't throttle me that slow. I would like a few suggestions from experience. Thanks guys, and gals...

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