Common wisdom says that Aquire is one of the pinnacles of American style design. It is a classic. One of the "few good games" from before the Eurogame period. Deep strategy. Brillant design. Multiple paths to victory (agressive purchases or money conservation). Player interaction.
It is one of those games that I plan to never play again.
The game is like Scrabble. You have six tiles hidden. You play one on the board in a specific place each turn. Each tile has one and only one place where it can be played. And you buy stock.
Most money wins.
Good luck trying long term planning with this game. You only have a hand of 6 tiles (so you know exactly one tile that you'll have 5 turns from now).
If Aquire is a "brain burner" due to the huge range of choices (play 1 of 6 tiles) then you'd probably want to stay away from Puerto Rico. There are eight different roles to chose from each round (in a five player game)!
Moving away from the "incredable depth" that playing 1 tile in a predetermined spot has, you also get to buy up to 3 stocks per round!
There are 7 different companies. Some of them pay out different amounts when they pay out. That's about the only difference between the companies.
So you buy stock in almost identical companies and play tiles in set board positions. 18xx is somewhat similar (stock buying and tile laying), except the tiles you lie in 18xx are train tracks and actually have some concrete connection to the financial sucess of the company that builds them. Come to think of it, 18xx does everything that Aquire tried to do but better and more thematically.
And 18xx games don't have the chance that you'll get a bad tile draw because there is no luck in 18xx (excluding 1829 mainline which I haven't played yet).
I personally would have more fun watching paint dry than being dragged into another game of Aquire.