[Perfectlap]

i have used every product widely used. Leatherique, Lexol, Meguiar's, etc.

The best at DEEP cleaning is 1Z which you can get on autogeek.net
It leaves a nice 'new look' matte finish, no residue or shiny film.
Use with a microfiber towel and you won't believe what comes off the leather.

For more frequent upkeep, Griot's Garage leather cleaner/conditioner in the tiny bottle stays in the door pocket. Also, no film residue and gets deep into those small creases that need to be minded before they become tears.