Without a doubt - Voigtländer Bessa I Color-Skopar 1:3,5/105
Number one would have to be my Rolleiflex f3.5, closely followed by my Blad.
I can see my latest analog acquisition becoming my favorite. With DOF and ML and good "era" lenses at reasonable prices my FT2 is my new darling. Next favorite shooter would have to have been my N80 for it's abilities at a reasonable price point.
My Graflex Pacemaker 4x5. I just enjoy using it, and it's been through a bit of travel and such with me. Never really had a problem, it's been as reliable as a working German camera. I have a studio monorail I really like, but if I want to use large format, I usually end up just reaching for the Graflex. It's just more convenient.
Also on my favorites would be my Seagull 4BI. Bought it for about $50, just had the focus go out last year (but it's just offset by an adjustable amount, and only prevents me getting closer than two meters to my subject.) I paid way too much for it, but it's been used so much and worked so simply and easily that I have gotten more out of it than I paid for it. Would never tell someone to buy one though. It's sitting in my cabinet outside of its case (as it no longer fits in it with the bad focus) and I can take it out, and the shutter, aperture, film advance (everything except the focus) is in perfect working order. I can't say the same about my Rollei, sadly.
35mm, I'd have to say the Minolta SRT-101. I first learned on that camera, and it was the easiest thing I had ever used. Line the needle up in the ring and your exposure is set right. focus on the lens. Push the side button for depth of field preview. Nothing ever was bad with the camera, except the battery switch could be a little more user-friendly. Haven't used it in years, but I still have it around, perhaps mostly for sentimental reasons. I wouldn't hesitate to recommend one of them for someone who wants to try film photography.
I love my M2 & M6, love my ETRS, but my favorite I bought it new when it came out; my OM 4T. It's been hundreds of miles hiking in deserts and mountains, taken pictures from Mt. Whitney to Badwater. It's taken pictures at Joshua Tree and Suicide, never been CLAed and it still works perfectly. Cosmetically it has a few flaws but so do I.
Rollei Wide Angle - Just gets on with the job with no fuss, is rain proof, dust proof and so far has been me proof
Despite a stable of cameras from a Minox B to a Kodak 2D 8x10, the Rolleiflex 3.5F (Planar) is the best camera I have ever used, period. The Gossen meter is still spot-on accurate, the camera is a pleasure to hold and use, the accessories are amazing. (I have a not-so-secret SL66 fetish, but I've never held one.)
Simple answer for me - Mamiya RB67 all the way. No hesitation with this question. I have a Pro-S and sorta wish i had bought an SD, but it's not too much different. I *love* the format, though 6x7 is harder for me to get C-41 films developed (like near impossible).
For smaller format, i really like my Minolta SRT202 and stable of excellent Rokkor lenses. I also have a KM 7D dSLR that is an absolute joy to use as well, but that's not an APUG appropriate answer!!!