What Teeka (commentary) of Sri Guru Granth Sahib Ji do you recommend?

Gurbani is Agam Agaadh Bodh. For this reason, you can’t find a perfect teeka (commentary). The best thing is to refer to the Darpan (Prof Sahib Singh’s teeka), and Giani Harbans Singh’s Nirnai i.e. Teeka, because both of these teekas are based on Gurbani Viyakaran (grammar). Apart from this one can refer to Bhai Veer Singh’s teeka called ‘Santhiya’ and Sant Kirpal Singh’s sampardayak teeka.