How can we choose more congenial Kammattana? Among the 40 Kammattana how can I choose more suitable Kammattana for me?
You will need trial and error but generally based on the personality types.

The Pali commentaries further provide guidelines for suggesting meditation subjects based on one's general temperament:

Greedy: the ten foulness meditations; or, body contemplation.

Hating: the four brahma-viharas; or, the four color kasinas.

Deluded: mindfulness of breath.

Faithful: the first six recollections.

Intelligent: recollection of marana or Nibbana; the perception of disgust of food; or, the analysis of the four elements.

Speculative: mindfulness of breath.


The six non-color kasinas and the four formless states are suitable for all temperaments.

Source: Kammaṭṭhāna

The forty subjects are also differentiated according to their appropriateness for different character types. Six main character types are recognized — the greedy, the hating, the deluded, the faithful, the intelligent and the speculative — this oversimplified typology being taken only as a pragmatic guideline which in practice admits various shades and combinations. The ten kind of foulness and mindfulness of the body, clearly intended to attenuate sensual desire, are suitable for those of greedy temperament. Eight subjects — the four divine abidings and four color kasinas — are appropriate for the hating temperament. Mindfulness of breathing is suitable for those of the deluded and the speculative temperament. The first six recollections are appropriate for the faithful temperament. Four subjects — mindfulness of death, the recollection of peace, the defining of the four elements, and the perception of the repulsiveness in nutriment — are especially effective for those of intelligent temperament. The remaining six kasinas and the immaterial states are suitable for all kinds of temperaments. But the kasinas should be limited in size for one of speculative temperament and large in size for one of deluded temperament.
Immediately after giving this breakdown Buddhaghosa adds a proviso to prevent misunderstanding. He states that this division by way of temperament is made on the basis of direct opposition and complete suitability, but actually there is no wholesome form of meditation that does not suppress the defilements and strengthen the virtuous mental factors. Thus an individual meditator may be advised to meditate on foulness to abandon lust, on loving-kindness to abandon hatred, on breathing to cut off discursive thought, and on impermanence to eliminate the conceit &quot;I am&quot; (A.iv,358).

Source: The Jhanas in Theravada Buddhist Meditation by Henepola Gunaratana
Anapanasati and 4 Satipatthana are generally safer type of meditations.