I agree with feenyxfire.
Best for whom? Most reliable for whom? The person living in New York city that never travels? The global business traveller? The guy in the backwoods of Upper Peninsula Michigan?
Lets apply the Guinness Book of World Records rule here - if it is quantifiable (measurable) then allow it. If it is qualitative (subjective descriptions like "best" or "unusual"), then it should not be allowed.
With cellular networks, that means a lot of claims would have to be thrown out. Best obviously. Fastest speeds? Proof of measurement - and if an over-generalization is made (we measured NY City speeds, so obviously that means we are fastest? No, that means you have the fastest speeds in NY City... and how did you measure that against your competitors?)
I can only use anecdotal evidence. I use both voice and tethering, and use a lot more internet connection time than I do chatting. I don't text (why buy a plan when I can put standard email on my phone?). In my area the complaints about AT&T have died down a lot due to a more recent upgrade, but Verizon is still better voice coverage when considering both urban and rural areas. Sprint actually has the best coverage in data - I can go more places and get a solid mobile broadband connection with them than Verizon. So, which is better? (It might help if you first try to define better fully, and then ask whether better was the right word to choose.) Which is more reliable? (Again, I think you have to define how you measure reliability before you can answer this one) Which is the fastest? (Which is faster - a 2 Mbps download, 28 Kbps upload, 190 ms ping connection that is not available 90% of the time or a 52 Kbps download, 52 Kbps upload, 70 ms ping connection that is not available 15% of the time? Hmmmm... guess we are going to have to define what is meant by fastest.)