Radars are absolutely crucial to success.
The rest are average. Orbital only gets 1-2 kills average, same for the Swarmer. Gunship is good for 2-3 average (sometimes it gets none!) and EMP only lasts a short time. Nanosuit usually gets about 3-5, but if you're on a 10 streak, you're likely already winning and some of those kills are ones you'd ahve got without the suit anyway.
Take radars out the game though, and the game is a very different beast entirely, and as Retriever lets you get them 50% earlier/more often, that's its real power.