Solar panels are a commodity item. If the wattage rating and physical dimensions fit your plan they are all about the same IMO. Actually if you will be going 12 volt and PWM controller it is best to compare Isc (short circuit amps) rating more than wattage. Best to have a controller rated at least 20% more than Isc. Find a local supplier to save shipping if you can.
Sealed AGM is great but do cost more. There is no magic to have GC2 in AGM format as that is more of a wet cell advantage. If you go four batteries then 6v is much easier to assemble a balanced battery bank.
I would go 3 to 4 panels (if they fit) if you do not have a generator. 2 panels is fine if you have a generator along.