OK, here is my take on tarpon fishing in Belize from many years of doing it. First of all you need to pick a guide that does the type of fishing you want to do. With the exception of the summer months, most of the tarpon fishing is done on the flats looking for the tarpon and then casting either by fly fishing or casting live bait or lures. During the summer months the tarpon migrate into the channels and they can be fished by anchoring and casting lures or using live bait. You also can troll, both in the channels and outside of the reef, using either live bait or lures. You can also drift fish using live bait. The tarpon can be concentrated in any of the channels from reef point to south of San Pedro. What I do with a guide for fishing this time of the year is to negotiate a price for the guide and boat and pay the guide for the actual fuel used. We might end up fishing one channel close to San Pedro if we find the fish there or we might go to reef point and troll all day looking for them. By paying for the fuel used, I do not have to worry about the guide not going to where the fish might be, and this changes from day to day, so I want the flexibility to do what ever we need to find the fish knowing that the guide does not have to worry about fuel being a factor. That is my take on it.
Now I know I did not answer your actual question as to what guide to hire. I would suggest you decide on how you want to fish and go to Steve and have him recommend a guide that fits your wants. Some guides will only offer one price and fish a predetermind way. Many will "customize" the day if they know what the customer wants. Combining the local knowledge of the guide with the style of fishing you want to me is the best of both worlds.
PS: Steve is who runs fishingsanpedro.com that Capt Jeff mentioned.