How would you rank the following?

AT&T's standerd iphone plan
T-Mobile's 5.99 T-Zones
T-Mobile's 19.99 Total Internet add on

I wouldn't pick based on speed alone. The speeds are going to be very similar as its limited to the technology ~ 200kbs

Picking your provider its much more important to make sure you pick the one with the best coverage and customer service that you can actually deal with. I go with the cheap T-Mobile plan because the coverage is the same for me and the customer support for t-mobile is by far better.

i would pick tmobile also in my area my friends with iphones on att cant make calls in as many places as with my tmobile. also the tmobile customer support is really great