For airflow vs cost you can do not a whole lot better than a fan from a mid 80s to early 90s Ford Taurus. Can usually be had at a junk yard for about $30-$40. Moves enough air to make your head spin. And it's a two speed fan. So you can wire it to run at the low speed below a certain temp and high only kicks in when you really need it.
Now, with great power, comes great responsibility.
That being said, the Taurus had a 160A alternator. Mainly because of this fan. From a dead stop to high speed the startup draw is close to 120A. However, once running the amp draw is not significant. So, in running this option, an upgraded alternator would almost be a priority as well. But for an electric fan, you can't get much better.
I have one sitting in the garage for the X. As soon as I do a Quest Alt swap, it's game time.