Dholak
The dholak is the drum that carries a room full of singers.
Bhajan, kirtan, qawwali, folk songs, weddings: wherever people sing together in North India, a dholak is usually keeping time. It is easier to start than tabla and rewarding on the first evening, which makes it the instrument we most often recommend to someone who wants to accompany singing rather than perform solo.
Dholak or tabla for devotional singing? Dholak. It is the traditional drum for group devotional music, quicker to learn, and loud enough to lead a hall without a microphone. Tabla is a classical solo and accompaniment instrument and a much longer road.
Why bolt tuning? A spanner and two minutes and the drum is in tune and stays there. Traditional rope lacing looks romantic and takes real skill to adjust, which is not what you want before a program.
Mango or sheesham? Sheesham is denser, slightly warmer, heavier and costlier. Mango keeps weight and price down and still sounds honest. If you play out regularly, take the sheesham.
Related: the naal if you want tabla articulation at folk volume, and All Indian Drums for the full range.