On race stuff, nothing! I hard wire everything. While that's not the easiest, it's the best.
The most popular connector out there is the Tamiya white connector. Honestly they are junk.
The best is probably WS Deans but they are a bit pricey. The connectors I like are Sermos/Power Poles/Lightspeed. They go by several names from several companies. They are the seperatable black and red connectors.
I'll dig up some pics later.