When I'm not shooting my 2 TLRs on a medium format day, it's either my Kodak Tourist 6x9 folder or Agfa Isolette 6x6 folder. I always get sharper results from TLR focusing than from guesstimating the range since my folders don't have rangefinders. Sometimes a TLR is too much to carry on certain journeys though, and the folders do great for crowd scenes, landscapes, things beyond 6-8 feet. On 35mm days I usually use one of my old Nikons or a Minox.
My TLR's are a Yashica A and Rolleicord III and a newly purchased Mamiya C330 which I have not had time to use. I had no clue how heavy the Mamiya would be, it will not be a walk around camera for me.
Currently I use a Minolta Autocord MX mainly because of the focus arrangement which does not require shifting the camera from one hand to another between shots to wind on as per most of the Rollei pattern types. Over many years I have used a Microflex, Yashicamat, Mamiya C33, Rolleiflex and Meopta Flexaret as well as 35mm, 645, 120 folders and home-mades and digital but I always prefer to use the TLR whenever possible. I make pinhole cameras and a 6x12 to use a Miniature Speed Graphic Kodak lens and shutter as well as pinholes. My digital camera is a NEX 5N.