My favorites are the 13" Ultimate, the 6x8 SEF, and the Pro coil. I have used several others, but like these three the best, and use them more than any other. The Pro coil is a great all-around coil. The 13" Ultimate is probably a tad deeper than the Pro coil, and really does a surprisingly good job in trash, for such a big coil. The only thing I don't like about the 13" is it is TERRIBLE at IDing nickels, for some reason. I can pick out nickels from within similar trash (beaver tails, etc.) really well with the Pro coil, and the 6x8, but when I try to dig nickels with the 13", I dig a lot of junk. A target hit when using the 13" coil, that would CLEARLY be a nickel on another coil, is most often NOT, with the Ultimate coil. It just does NOT like to ID nickels consistently. Finally, I find the 6x8 to be a really smooth, stable coil, and it is surprisingly deep -- it is ALMOST as deep as the Pro coil for me, and yet better in trash given it's size. If I had to pick only 3 coils, these are the three...
By the way, I will be selling several Explorer coils in the near future, as I'm getting a second Explorer (to have as a backup machine) from a friend this weekend. Along with his Explorer, he is selling me about 8 coils that he has to go with it. I am thinking right now that I will probably keep the three I mentioned above (he, like me, really likes those three coils), but will likely sell at least a few of the rest; the coils I may part with would include a 12" SunRay X-12, a 15" WOT, a 10x12 SEF, and an 18" Excelerator; I may also part with his 5" SunRay X-5, not sure yet. Please send me a PM if any of you are interested in any of these coils.
Steve