Graha Mantras from Garuḍa Purāṇa

oṃ gurave namaḥ

oṃ mahagaṇapataye namaḥ

oṃ namo nārāyaṇāya

Graha Mantras from Garuda Purāṇa

The best mantras for Grahas are those given in the Vedas and Purāṇas.

Here are the graha mantras from Garuḍa Purāṇa, Chapter 16 - Viṣṇu Dhyāna

ṛṣi bhṛgu

sūrya - oṃ khakolkāya namaḥ

this is the mula mantra of sūrya

Nyāsa mantras

oṃ vici ṭha ṭha

oṃ jñānine ṭha ṭha

oṃ sahasraraśmaye ṭha ṭha

oṃ sarvatejoSadhipataye ṭha ṭha

oṃ jvala jvala prajvala prajvala ṭha ṭha

Surya Gāyatri -

oṃ ādityāya vidmahe viśvabhāvāya dhīmahi tannaḥ sūryaḥ pracodayāt

With this Gāyatri, the worshipper should perform the Sakali-karaṇa rite

For the 8 directions

Purva, East - oṃ dharmātmane namaḥ

Dakṣina, South - oṃ yamāya namaḥ

Paścima, West - oṃ daṇḍanāyakāya namaḥ

Uttara, North - oṃ vivarṇāya namaḥ

Īśāna koṇa, NE - oṃ śyāmapiṇgalāya namaḥ

Agni koṇa, SE - oṃ dīkṣitāya namaḥ

Nairṛtya koṇa, SW - oṃ vajrapāṇaye namaḥ

Vāyu koṇa, NW - oṃ bhūrbhuvaḥ svarnamaḥ

Graha mantras for different directions

Purva, East - oṃ candrāya nakṣatrādhipataye namaḥ

Agni Kona, SE - oṃ aṇgārakāya kṣitisutāya namaḥ

Dakṣina, South - om budhāya somaputrāya namaḥ

Nairṛtya Kona, SW - oṃ vāgiśvarāya sarvavidyādhipataye namaḥ

Paścima, West - oṃ śukrāya mahaṛṣaye bhṛgusutāya namaḥ

Vāyu Kona, NW - oṃ śanaiścarāya suryātmajāya namaḥ

Uttara, North - oṃ rāhave namaḥ

Iśāna, NE - oṃ ketave namaḥ

It is interesting to note that all the graha mantras except those of the Sattvic planets Candra and Guru, are referring to them as children of their parent. For Candra and Guru, the mantra refers to their overlordship of all Naksatras and all Vidyas.

The direction mapping of the grahas, maps to the Kalachakra scheme to some extent, but diverges in case of Moon and its nodes. In the Kalachakra, NE is ruled by Rahu, while Moon rules the North. Sun itself rules the East and Ketu doesnt rule any of the planar directions.