No modifier = very important action
Ctrl modifier = important action or related/inverse to the action that use the same key but without the modifier
Alt modifier = might come in handy action
Ctrl + Shift modifier = rarely useful

---Modelling---
Select Sub-Object Ring    : Ctrl+W
Select Sub-Object Loop    : Ctrl+E
Select Edgeloop down add  : Up Arrow
Select Edgeloop up add    : Down Arrow
Select Edgering down add  : Right Arrow
Select Edgering up add    : Left Arrow

Grow Selection            : Spacebar
Shrink Selection          : Ctrl+Spacebar
Connect Settings          : C
Connect                   : Ctrl+C
Distance Connect          : Alt+C
Target Weld               : T
Collapse                  : Ctrl+T
Chamfer Settings          : F
Chamfer Mode              : Ctrl+F
Inset Settings            : Q
Bevel Settings            : CTRL+Q
Edge Constraint Toggle    : "key above tab" (which in my keyboard has a different symbol than most)
Face Constraint Toggle    : Ctrl+"key above tab"
Norm Constraint Toggle    : Alt+"key above tab"
Attach                    : A
Detach                    : D
Bridge                    : B
Cap                       : Ctrl+B 
Cut Mode                  : V
Swift Loop                : Ctrl+V
Quick Slice               : Alt+V
Make Planar               : Ctrl+0 (works also with Ctlr plus the 0 from the numpad)
Invert Selection          : Alt+I


---SubObject visibility---
Hide Selected             : Ctrl+H (for some reason this keybind doesn't work, despite it isn't conflicting with anything)
Hide Unselected           : Ctrl+I (for "isolate")
Unhide All                : Ctrl+U

---Object visibility---
Hide Selection            : H
Hide Unselected           : I (for "isolate")
Unhide All                : U


---Pivot---
Affect Pivot Only         : Ctrl+P



Perspective User View     : F5
Orthographic User View    : F6
Transform Gizmo Axis Constraint Cycle : F7
Expert Mode toggle        : Shift+X
Zoom Extents              : P
Reset X-Form              : Ctrl+Alt+X
Snap Toggle               : S
Snap Quad-Menu            :Ctrl+S

--Changed or Removed---
Viewport Background       : Ctrl+Shift+B  (assigned to free Alt+B usage)
Edit Soft Selection       : Alt+B (assigned to free B usage)
Sound Toggle              : (removed to free "the key above TAB")
Camera View               : (removed to free "C")
Create Camera physical from view : (removed to free "Ctrl+C")
Edge Turn                 : (removed to free "Ctrl+T")
Clone                     : (removed to free "Ctrl+V")
Select by Name            : (removed to free "H")
Hold                      : (removed to free "Ctrl+H")
Group Attach              : (removed to free "Ctrl+U")
Orthographic user view    : (removed to free "U")
Perspective user view     : (removed to free "P")
Transform Gizmo Constraint X : (removed to free "F5")
Transform Gizmo Constraint Y : (removed to free "F6")
Transform Gizmo Constraint Z : (removed to free "F7")
Select Object Active Shade   :  (removed to free "Q")
Constraint to Edges          :  (removed to free "Shift+X")
Keyboard Shortcut Override   : removed
Pan Viewport                 : (removed to free "I")
Save File                    : (removed to free "Ctrl+S")