I'm going to say that Bluefin is the best charger map. Or at least the best E-Liter map.
A lot of people on this thread are saying that Moray is a good charger map, which is typical for one to say. But the reality is that having an E-Liter on Moray is actually a huge detriment to a team, especially if the other team doesn't have one. This is because if the E-Liter is taken down just once, which is VERY possible even on Moray, the game has ended for it. Once you remove it from its position, your team has enough time to get onto the enemy's snipe, wreak havoc on their side of the map, and essentially render the E-Liter useless. The E-Liter won't really be able to paint, and as such it's a 3 v 4 because it died one time, and it's not going to be able to do its thing anymore.