You know this is kind of a harder question to answer than one might think it would be. its like having children I suppose - you love one a bit more for one reason and you love another a bit more for a different reason. But overall you love them all. So I have made a distinction between my favorite "user" and my favourite camera "jewellery".
The camera I perhaps use most frequently these days, is an an "optioned up" Olympus OM D EM5 (i.e. with supplementary hand grip, + battery grip etc). The basic camera is too small for my hands on its own but with the extra grips (for some reason - maybe economics - Olympus made the accessory grip in two separate parts) it is just right with nice balance and handling. And it looks cool. Just like a baby Nikon D800 or something. It is a very nice camera to use with brilliant 5 axis vibration reduction, its only significant fault being that it does not have focus peaking (in the Olympus line that came later in their line of cameras). This is the child which is smart, good at almost everything and you know will grow up to become a doctor and discover a cure for an otherwise incurable disease.
On the other hand, having had a love/hate relationship with my Leica M8 for quite a while, I have recently had a resurgence of love for it. And I might be inclined to say it is my present "emotional" favorite, if that makes sense. At least for now. I still struggle to focus adequately with its antiquated rangefinder system (and my antiquated eyes) but I am presently enjoying trying. Its main flaw I have decided is that on the one hand it is difficult to focus fast lenses well, especially if you like standard and longer lenses as I do. Which forces you to stop down but because it has a CCD sensor, it lacks the ability to ramp up the ISO to compensate when shooting in adverse light. This is the child I love because it is beautiful and sweet, but know in my heart of hearts that it is as dumb as a bundle of sticks.
Oddly my renewed love of the M8 may have something to do with the fact that I recently lashed out and bought a Leica Q. The camera is superb, it has a superb lens, a very nice/competent sensor which produces excellent IQ and quick and competent AF. But I quickly found that the very things I love about the Leica Q are the very things I dislike about it. That is, I can rely on the camera for most things - all I need to do is point, and shoot. I do not need to think much about what I am doing.
Years ago psychologists were conducting experiments on rats. They found that if you rewarded a rat with food when it pushed a button it kept pushing that button. This is no surprise. But they then also found that if you only SOMETIMES rewarded a rat with food when it pushed the button the rat went ballistic and become addicted to pushing the button like crazy. My hypothesis is this is what happens with humans who become addicted to poker machines in Vegas. It is also my hypothesis that it is what happens with photography aficionados when we use Leica M8s and their manual focus lens - we sometimes get results and that intermittent feeling of gratification is so pleasurable we keep on pressing the (shutter) button like crazy.
Least that is what I think. 🙂