I'd choose second if not for the placement of town plaza and the pond in front of the station. The placement in the first is much more ideal in my opinion. They aren't getting in the way and looks like you have more space for pwps.
Not many replies yet, but I would say the majority of players would go for the first map - albeit that hasn't happened up to now!
I like R-Tail relatively close to the dock and you have that in both maps - I'd try walking from the dock (well the top of the ramp, as the game doesn't allow you on the beach at this stage) to see how the 2 maps compare in ease of getting from dock to re-tail.
I would walk around the map to see how well it 'flowed' - how easy it was to go from major points (civic buildings, campsite entrance) - are there any rocks or ponds very much in the way - ie not easily get roundable.
I personally like narrow strips of land -especially at the top by the railway tracks - wide enough for alt houses/out of the way hybrid breeding plots/whatever. And both maps have that. But a lot of players don't like them.
The narrow slip of land by the campsite is not so easy - probably enough to prevent me picking this map as a keeper.
Rivers with long horizontal stretches can be frustrating for balloon popping, in the last town I set up (& I have too many) I specifically looked for a mainly vertical river just cos of this. (I like popping the balloons as we now get Harvey items & other non balloon furniture).
Does one town have starter villagers you would really like to have? Does one have the native fruit you would rather have?
I can't really pick between either, both have good points and bad, I would probably continue to reset until one map popped out as a must have. Must have in your terms, there isn't a bad map as such, it depends on what is important to you.