Carcassonne Central

I want to make my own board game, and Carcassonne is a main inspiration. I have couple of questions

1.I don't know if I want the tiles to be hex or square. +/- of them?
Hex
+ More edges.
+ Could be smaler number of tiles
- well, it's hex
- difficult to place in gaps

Square
+ Simple in design, and doing
- can't think of anything

Got anything else?

I want do a game that have some of features placed in Carcassonne (city building, roads, and farms). Beside that there would be some trading. For now i have in mind tokens of trading post, ports, and farms. The main theme would be sending traders to gain profit.

For now the gameplay would be something like that.
Players build some starting map from starting tiles. On them would be cities, and lots of roads. Next players would place normal tiles with places for farms, ports, rivers, and similiar. And so on. I would like to game end when one of the players would gain dominations over the map, or gain certain amount of victory points.