The answer is simple. Just ask yourself how much attached you are to this material life. How much material desires do you have? Do you like the life experience here? Depending upon the answers and what you feel, you can easily decide what path is suitable for you. Because the scripture says as below:
nirviṇṇānāṁ jñāna-yogo nyāsinām iha karmasu
teṣv anirviṇṇa-cittānāṁ karma-yogas tu kāminām [SB - 11.20.7]
Among these three paths, jñāna-yoga, the path of philosophical speculation, is recommended for those who are disgusted with material life and are thus detached from ordinary, fruitive activities. Those who are not disgusted with material life, having many desires yet to fulfill, should seek perfection through the path of karma-yoga.
yadṛcchayā mat-kathādau jāta-śraddhas tu yaḥ pumān
na nirviṇṇo nāti-sakto bhakti-yogo ’sya siddhi-daḥ [SB - 11.20.8]
If somehow or other by good fortune one develops faith in hearing and chanting My glories, such a person, being neither disgusted with nor very much attached to material life, should achieve perfection through the path of loving devotion to Me.
So the rule is simple:
- If you are not interested in material life then follow path of jnana (dhyana is primary part of it)
- If you are attached to material life and have material desires without much interest in God and spiritual things then follow path of Karma.
- If you neither too detached, nor too attached and have faith and interest in God, then follow path of bhakti.
Irrespective of which path you follow, if you do it properly then it will automatically lead you to the other. However, in this present age of Kali, following the path of jnana is very difficult. So generally path of devotion can be easily followed by most people without any risk. And bhakti (devotion to God) gives the result of all the other paths:
yat karmabhir yat tapasā jñāna-vairāgyataś ca yat
yogena dāna-dharmeṇa śreyobhir itarair api
sarvaṁ mad-bhakti-yogena mad-bhakto labhate ’ñjasā
svargāpavargaṁ mad-dhāma kathañcid yadi vāñchati [SB - 11.20.31,32]
Everything that can be achieved by fruitive activities, penance, knowledge, detachment, mystic yoga, charity, religious duties and all other means of perfecting life is easily achieved by My devotee through loving service unto Me. If somehow or other My devotee desires promotion to heaven, liberation, or residence in My abode, he easily achieves such benedictions.
So ask your self those questions and depending upon your state of mind you can easily decide which path is suitable for your current situation.