Eclipse 5.3 (6.5" concentric . . .Yeah, I wonder why it wasn't named the Eclipse 6.5 also.) I feel it provides the most pro's vs the fewest con's, most importantly it has what I call the "big 3". (1) "Access" - the physical size allows you to actually get your coil over a significantly larger percentage of ground (harder access, less-hunted ground at that) and since the mantra is "you gotta get your coil over it . . ." this is the most important aspect IMHO. (2) "Separation" - much more important in most areas than pure depth which, at 6-7" the 5.3 is no slouch at. (3) "Weight" - pretty obvious that lighter means longer, more comfortable hunts but the most significant thing about a lighter coil is it makes it easier to have good, consistent coil control (swing speed, coil orientation, etc.) which is very critical. This all adds up to a lot more good finds and fun hunts for me so the factors really have to force my hand to get me to change from my go-to 5.3 to another coil.