I have been using Deans Ultra plugs since they came out like 15 years ago (mid 1990s). At the time they were the lowest resistance connector out there. I don't think that is true anymore.

The Sermos/Powerpole connectors are the red and black spring connectors that snap together and have been around forever. I know they were around in 1990 at least, and probably before that. There is nothing wrong with them really, they just seem like an old design to me.

The Deans Ultra Plug also has its weaknesses. They are kind of hard to solder. It takes a fair bit of heat to solder a 12 gauge wire on it, and leave the iron on a second too long and the whole plug melts. Weak!

I think the biggest weakness with the Deans Ultra Plugs are that the solder joints are exposed and have to be covered with heat shrink. The heat shrink is rubber, so it will degrade over time.

In theory I think the gold bullet and tube connectors that Orion and all the Euro companies sell seem like the best idea, except that you have to coat them with heat shrink tubing which can tear and will degrade over time.

I saw that somebody posted a link of those same bullet and tube type connectors that had plastic covers on them to provide insulation. That seems like an excellent design.

The other interesting option is the Losi EC3 connector. It again is a variety of the gold bullet and tube connectors, except the tubes and bullets are snapped into a plastic connector to provide insulation. The only downside to these is that it seems a little difficult to get the metal tubes to snap into the plastic parts. I have not done it myself. When I saw somebody else do it it seemed to take a fair amount of effort. There is also an EC5 connector that is basically the same thing, except it uses larger diameter gold tubes and bullets for the extra current in 1/8th scale cars.

Anyway so I was thinking about switching from Deans Ultra and will probably try one of the gold bullet and tube setups that also have plastic insulation on them.