First, I'd start with any other broadband providers at your location.
This is very location specific, but also easy to find out. Here for
example, Cablevision is one TV/internet provider. Verizon/FIOS is a second
option for some towns. There are usually only one or two, because
it's expensive for competitors to run new infrastructure. Typically one
knows what is available because they get bombarded with offers, TV ads, neighbors have it, etc. Those would typically be the best performance
options.
After that, what's available wifi again depends on your area. Before
buying anything, you need to find out what's there. Here for example,
the cable company, Cablevision, has many hotspots deployed in various
areas. But they tend to be more in the commercial areas, from my
experience and you also have to be a customer of their regular internet
service. Whatever exists where you are, you need to be within
range. Around here and I would think in most of the USA, your
chances of picking up a public, open wifi is slim. I'd ask neighbors
what they are using. Have a notebook or smartphone? What wifi shows
up on it? At my house, the only thing I see are the neighbor's wifi's.
Did you fully pursue whatever the issues were with
AT&T? Many times folks blame the internet company when the problem
is actually something on their end.