I have and love an MRT VX Pro, a UK based company so it seems it's not as well known anywhere else in the world. They're very high spec and have lots of things to change, like punch, drag brake, brake strength, launch control start punch, most with 14 levels. The launch control works very well, it lets you just nail the throttle off the start line and if you're reactions are good when the buzzer goes you're likely to gain considerable distance on other cars. They're not the lightest of speedos but thats partly because of a fairly tough case and more from the fact that it's totaly waterproof, they coat the insides with something like silicon gel, like you would use around the edges of a bath. It uses small gold plugs instead of soldering straight onto the servo, so you can't damage the internals by heating it too much, plus it's easy to have a car wired up and just unplug the speedo to swap it into another car, the plugs are a good fit so don't come out in a crash. I have blown mine up but that was from connecting my cells the wrong way round and not noticing for a few minutes, until club mates saw smoke infact
sent it back and got it repaired for less than £20, including a new FET and case, since the case had melted a bit in the heat, I couldn't even unplug the cells, they unsoldered themselfs in the end
Another nice point is it doesn't have one of those weedy dangling switches that people don't seem to secure properly so they get ripped off, it has just one button on the top and 6 LED's to tell you what you're doing.
There's a sport version with very similar specs, the Sport is around £95 and the Pro can be found for £125, possibly less. There are plenty of them at my club, most people turn to them after blowing up LRP's or similar