Which cellular data card network has the most reliable coverage and speed?

I think that Sprint or Verizon are your best bets. They have the best coverage.

It really depends on where you are, and where you live. T-mobile has really highly rated network reliabilty, but I’ve found that in San Francisco it’s not so great. I’ve had Verizon in LA which worked well, except in my apartment where it didn’t work at all. AT&T has been fairly good all over, but occasionally drops signal.

They all stink; it really depends on where you’re using your phone.

So if it depends on where you live, and I live in Portland, Oregon, do I just look at provider-supplied data coverage maps and hope that they are correct?

I think most providers offer a 14 days return policy. Check your reception. Just make sure you don’t get a phone before you work out of town, like I did.

Followup: Just had a great experience ordering online from Sprint. Chat agent walked me through the entire process and answered all questions, checking coverage too. Between sprint and Verizon, sprint is the only one that has an unlimited data plan at $59/month. I am on a Mac and got a USB card, model Ovation U727. It comes with a 30-day period in which I can return without penalty or early termination fee. Connect with me via Twitter and ask me in 30 days if I am still happy with it. http://twitter.com/AdamBoettiger

verizon no trouble at all and its fast..

Installed the Sprint Novatel Wireless Ovation U727 USB EVDO card on MacBook Pro. Indoor speed test: 2.4 MBs DL / 705K UL. Nice. Tomorrow: Mobile test on bus and train.