If someone can read only one of Bhai Sahib Randhir Singh Jee’s books, then I think Gurmat Bibek would be the best choice. If two, then Gurmat Bibek and Gurmat Adhiatam Karam Philosophy. The reason for this is that Gurmat Bibek provides detailed guidance on living a practical daily Gurmukhi Jeevan which is far higher than any knowledge or preaching. Bhai Sahib has written many times, across his books, that the Hukams are there written in Gurbani for us to find and follow every single one. “ਗੁਰਬਾਣੀ ਪੜੇ ਸੁਣੇ ਦਾ ਕੀ ਲਾਭ, ਜੇ ਅਨੁਸਾਰੀ ਹੋ ਕੇ ਇਸ ਉਪਰ ਚਲਣਾ ਨਹੀ?” (ਅਣਡਿਠੀ ਦੁਨੀਆ, ਸਫਾ ੨੬੭)
Aside from unequivocally proving the superiority of Gurmat deeds (Naam Simran and Hukam Razayee Chalna) over all other activities and actions, Gurmat Adhiatam Karam Philosophy is a particularly valuable read because it often concisely summarises many of the key topics expanded upon in several of Bhai Sahib’s other books including Gurmat Naam Abhiyaas Kamayee, Katha Kirtan, Naam te Naam da Data Satguru, Gurmat Gauravta, Sant Pad Nirne, Anditti Duniya, Gurbani Laga Matra di Vilakhanta, Gurmat Sach Nirnai, Charan Kamal Ki Mauj, Anhad Shabad Dasam Duar, and Sachkhand Darshan.
Of the three books containing compiled articles (Gurmat Vichar, Gurmat Lekh, and Gurmat Prakash) I think Gurmat Vichar might be the most beneficial to read. Many keen paathis very much like Gurbani Laga Matra di Vilakhanta for its indispensable and sharp perspective.
The lofty and expansive vocabulary combined with an expounded, erudite, and powerfully poetic writing style does not make for easy or casual reading. Almost everyone will require a dictionary, maybe two.
Some of the audiobooks are also available.
Unfortunately, some of Bhai Sahib’s strictest and most uncompromising words have been edited in the newer editions of some books. It would be honourable if this small but important issue could be addressed at an appropriate time in the future and all original content be restored.