There are some civs that have a unique building that is just overwhelmingly awesome, clearly superior to the standard version. You're going to build it anyway so making Building+ feels great and is a huge advantage. Stele and Wats and Mud Pyramids and such. Then there are those civs that boost the resources you are going to improve anyway or the tiles you work anyway or the tech path you are going to follow anyway. The civs that are so good that they drop the difficulty. It's hard to play an actual Incan Deity game. Or Shoshone. Or Poland.
Then there are the civs that make you tweak your play rather than reward you for doing what you were going to do anyway. Those civs are usually not that popular. Venice gets a lot of guff because it is such a departure from standard operating procedure. Polynesia encourages you to crank out some Warriors, of all things, and also improve tiles with giant, stone heads rather than mines, farms and trading posts. Denmark wants you to swim at your enemies then crush them, drive them before you, hear the lamentation of their women. Indonesia wants you to immigrate to other lands in search of spices.
If you like the tried-and-true Archer-CB-XB tactic of course you love the Archer-CB-Longbow or Cho-ko-nu tactic and so England and China have a lot of fans. Personally I like to occasionally mix it up a bit and play the civs that make me look at the map differently.