3 and #4 for me on the favorite Tesoro models I use and the types of sites I enjoy hunting.
Now, #3 & #4 are both 8" 'donut' shaped Concentric designs, but the 'brown' colored 8" is #4 because I personally prefer the original 'white' colored 8" Concentric coil. Those were on models like the early Royal Sabre and several others back in the '80s, and I most especially enjoyed it on the 'original' Bandido that came out in March of 1990. After that they made a change to the brown 8" 'donut' coil that was still a very good coil, but it was a little thicker and heavier than the original white-colored 8" Concentric.
Next on my list at #5 would be the slightly 'Out-Of-Round' or 'OOR' shaped 8X9 'spoked' Concentric coil. I started using the 'OOR' term to describe those coils when introduced about the latter '90s because there aren't round shaped, but they are closer to that than the very pronounced oblong or elliptically-shaped 'pointy' coils we see quite often. The 8X9 'OOR' Concentric coils are OK, and they work just fine .... for most folks.
But that just slightly 'Out-Of-Round' configuration seems to actually make Pinpointing just a little more difficult for some people I have noticed. Also, I never really noticed any enhanced abilities of the 8X9 compared with either white or brown 8" Concentric coils. Matter of fact, I have had just a bit better depth results on naturally-located targets when I have compered the 8" and 8X9 afield. Not a lot, but it was noticeable.
So, why are the 8" Concentrics in white or brown only my #3 and #4 coil picks? Because I have been detecting for over fifty-two years as of last March and the bulk of my sites-of-choice are quite littered, often with a lot of ferrous discards. Therefore, smaller-size search coils tend to work better. My #1 and most used coil is the thin-profile 6" Concentric and my #2 favorite is the new 'Precision' 7" Concentric that came out standard on the Mojave. I like its weight, balance and 'feel' and, when comparing coils in-the-field for general, all-around hunting, I favored the new 7" Concentric over the 8" coils [size=small](either color)[/size] and naturally over the 8X9s spoked design.
But, if I was limited on coil choice between the 8" round 'donut' and 8X9 'OOR' shaped Concentric coils for any of my favorite Tesoro models, it would easily be the 8".
I also have a 4-pin Vaquero and don't have any 8" or 8X9 coil for it, preferring the thin 6" Concentric most of the time, and if I want coverage and a little better depth, I swap to the 8X11 DD that came standard on my newer black-version Vaquero.
Monte