Camera's that I tend to bond with are usually very fit for purpose and/or have an instinctive UI
Bonded:
Nikon FM > simple, sturdy, always good results.
Nikon FM10 > it may be plastic, but looking at ergonomics this is the best camera ever. Punches way above its weight.
Olympus Mju-II > A true, foolproof, blazing fast point & shoot.
Polaroid 195 > knobs, levers galore, yet easy to understand, use and love.
Nikon D70 > My first digital workhorse, practically was married to it.
Olympus PEN EE-3 > So lovely and retro and simple, has no right to work this well, but it does.
Minolta Dynax 7 > The best 35mm camera I have ever used, manages to pull off that very difficult trick of merging high-tech with a great UI. Besides, world class auto focus.
Yashica Mat 124 > Fantatstic lens, surprisingly easy to use, portable medium format.
Canon Canonet GIII QL17 > Quintessential small rangefinder, extremely well suited to my style of photography, impossibly good lens for the price.
Polaroid SX-70 > Weird yet sexy, great concept.
Not bonded:
Sony NEX-3 > Odd ergonomics, terrible UI. Good results though.
Nikon D600 > Great sensor, but feels big and clunky. Unforgiveably poor auto focus with older 'screwdriver' lenses. Impossibly long winded menus.
Olympus XA > Too small and fiddly and fragile.
Werra 3 > Just too weird.
Fuji Instax 210 > Oversized, clunky, primitive.
Hasselblad 500 C/M > Wonderful engineering and results, but ergonomics were not considered. Clunky.
As for my Leica M2, I am on the fence. It is a solid and beautiful camera, capable of great results. But is also fragile and slow. In my mind it is no match for any decent mechanical Nikon SLR. Heresy, I know.