Commonly used connectors are:
Dean's Ultras - They are polarized (positive can only go to positive, neg only to neg), have an 80A current limit, and make a very solid connection. They can be difficult to unplug though, the female end of the connectors (used on battery end) are shielded, but the male connector is not.
Astro Flight Zero Loss: Polarized, 50A current limit. Make a solid connection. Both male and female ends are shielded. But they are expensive.
Kavan Gold "Stecker" Connectors: Polarized, 75A limit, make a solid connection, both male and female are shielded. Easier to separate than Deans, but not going to fall off. But they are expensive.
(mid-way on the page)
E-Flite EC3: Polarized, 60A limit, make a solid connection, both male and female are shielded. Relatively easy to separate, but unlikely to disconnect by themselves. Reasonably cheap.
http://www.e-fliterc.com/Products/Defau ... =EFLAEC303
Anderson Powerpoles: One of the most popular connectors. Polarized, both male and female shielded, there is no specific male and female side, have a 15-180A limit depending on the model. Now that patent has expired, getting increasingly cheaper. On larger plugs can sometimes become difficult to separate(which is both good and bad).
http://www.andersonpower.com/products/s ... rpole.html
Tamiya connector (often called a "standard connector" in the electric R/C world): Polarized, 20A limit, both male and female plug shielded. Individual connectors loosen in the plug over time and doesn't make a solid connection always. Can be difficult to separate (plastic is slippery)... and yet, occasionally will separate by themselves. Usually cheap.
Molex connector: polarized, both male and female shielded. Suffers from similar problems as tamiyas. Usually very cheap.
For what it's worth, at one time or another, I have personally used every one of these connector types. Of the list, I normally use Dean's and E-Flite EC3's... but that's because a local store sells them fairly cheaply. Without my local store, I'd probably be using Anderson's Powerpoles. I personally would recommend that E-vehicle users avoid Tamiya and Molex connectors. I've had them fail on me.
9Continent 2807/700C, 36V 25A Infineon controller (w/ regen), 48V 15Ah "Ping" LiFePo battery