I have three books describing double bass positions but each of them are different. ‘York Studies for Double Bass’ describes second position as first finger on B flat, on the G string. ‘The Study of Orchestration’ (Samuel Adler) describes second position as first finger on B natural. ‘Practical Tutor’ (Adolf Lotter) has explanations of ordinary position and medium positions along side traditional positions. I was wondering what, if any, systems of left hand positions to use. I have not been playing long and my teacher uses Simandl technique so Rabbath’s positions are not an option for the time being.
I realise that any of these systems can be used if you are consistent with their application but is there one that is more popular?
Thanks for any help.

You will not be surprised that I don't have an authoritative answer for you, since I never had any bass lessons. However, I have had a lot of helpful advice from better players than me, and on reflection can remember no occasion when any of them used a position number to indicate a point of fingering. I suppose that is a small amount of evidence that the most popular position numbering is "none". To indicate a fingering in a part I use Roman numerals for the string and Arabic for the finger.