I bought a Titus El Guapo frame on the cheap cause they went out of business, WHAT A BIKE!! I Love this frame! I have ridden Enduros, Fisher Fat Possums, and the El Guapos run all over them. You can find them on Ebay here and there. 6" travel bike, rides like a 4" xc rig, but eats up descents. I truly grind in the saddle, and no pedal bob. I have ridden this bike on epic back country rides, and used it for Downhill at Kicking Horse in BC, and it excelled at both, though I didn't do any Black Diamond downhill, but I have no illulsions of being that good, lol.
If you can't find an El Guapo, I would look at the Pivot bikes, like the Mach 5.7. Pivot was started by the original owner of Titus, so same concepts, only better. Excellent all purpose bikes.
Giant VT 5.7" rear travel run with 150mm (6") RS SEKTOR coils. the Sektors can be run as low as 90mm (U-turn) but started at 150 tried 140 but was WAY better in 150mm mode. This bike was well rated by the press when new. Nowadays we are all told 67 degree head angles etc are essential BUT this baby really rocks up / down / singletrack, very versatile. Can get them here on pinbike otherwise move on to Giant Reign or find a Nomad, who cares they are all good its down to the rider & getting the set up tuned to your body & riding style. No way does an off the shelf bike "really" work for individuals which we all are...of course.
My Enduro is super nice. I wish I had gotten the carbon frame version because it would make the bike that much more sick! I think it climbs like my dads stumpjumper 29er but decents way better, it's a mini dh bike when pointed downhill.
I'm only selling my 2011 expert enduro bc I was in a position to buy the carbon version this year. I thought about even unloading my demo 7 and just having an enduro Evo and the carbon pro.
THE BIKE IS JUST THAT SICK.
I know personally 3 people who have lovely bikes of their own, and once or twice they rode my enduro out of circumstance. They all walked away astounded.
There are probably too many AM rigs out there that will fit the OPs bill. Everyone is going to have their own opinions and preferences. If you prefer one of the 3 that you originally posted, then I'd say to go with the Yeti SB-66. I've tried a friends and for a bike with 6" of travel, it climbs surprisingly well and descends like a beast. Could also look into the Pivot Mach 5.7. I love Rocky Mountain bikes and although I haven't tried a Slayer, but I've heard the Slayer 70 is a kick-ass do it all bike.