Which calendar should i use?

Okay i'm searching more and more about this fascinating religion, Now i found multiple calendars used by the ancient greeks.

Do the gods/godesses have any favour?

If not which one is the easiest to use?

Currently by a quick search on wikipedia i found these calendars:

-Attic
-Boeotian
-Cretan
-Delphic
-Epirotic
-Laconian
-Macedonian
-Rhodian
-Sicilian

The dates for important festivals and ritual occasions do not vary all that much between any of the Greek calendars or even the Roman calendar (in which the major Greek religious festivals nearly all have counterparts).

The various Greek calendars all functioned in roughly the same way, the only difference between most of them being the names of the months (most of which have been lost long ago).

The Attic calendar is rather well attested, but actually, it had fallen out of use already in Antiquity, starting in the Hellenistic era, and was largely replaced by the Macedonian calendar (which became known simply as the 'Greek calendar'). It is also lunar, with months lasting from one new moon to the next, with intercalary leap-months inserted every two years, rather than every four as in the Attic calendar.

However, I would advise you not to put too much worry into calendar usage. Worshippers in Greece do not make much use of the archaic calendars at all.

In the Orphic tradition, we still use the astrological calendar that became popular among religious groups beginning around the first century CE, which is different from the Greek civil calendars entirely.

Most of the festivals you will see mentioned in the calendars of particular cities were local, public holidays that would have only been celebrated in those particular areas, and which had, usually, only a minor religious significance (usually tied to events in that city's history).

What matters are the cosmopolitan, universal festivals celebrated all over the Classical world — and these are the ones still celebrated by worshippers in Greece, both new converts, and adherents from familial lines.

These are:

i. Theogamia: the festival of the divine marriage of the Father and Mother of Gods (typically Jove/Ζάς and Juno/Ἥρα in this festival). Occurs in late winter, usually around early/mid-February. It is a festival of love and prosperity, roughly equivalent in time and significance to the Roman Lupercalia.

ii. Spring Bacchanalia: a rustic festival of early spring, around early March, associated with the opening of new wine (and all the associate higher symbolism of this), it is likewise a celebration of spring, and a time to make offerings to the dead. It is equivalent to the Roman Feralia or Liberalia and merged in Antiquity with the other spring bacchanal holidays of Greece, the Lenaea and the Rustic Bacchanalia. It is traditionally celebrated over three days.

iii. Adonia: a festival of late spring/early summer, usually some time in April, associated with the cyclical death and revival of Adonis, and the parallel course of the human soul. Adonis is honored and his death is lamented. Traditionally, there would be processions of mourners through cities who wept for Adonis. Also, people would plant annual flowers, with which Adonis is associated for obvious reasons, which would be allowed to wilt and die at the time of the Adonia. This is a symbol of the divine spirit (as the beauty and fragrance of the flowers and foliage) within a mortal body, which must experience death (as the plants die and flowers fade) so long as it is bound to such a body. In the Orphic tradition, especially in Greece, it is celebrated, out of convenience, to coincide roughly with the Orthodox Easter.

iv. Thargelia: the spring festival of the births of Apollo and Diana, the twin children of Leto. It is a festival of purification, and is associated with fasting and other purificatory practices. These deities are worshipped, and offerings are made, traditionally by children with living parents, of olive or laurel branches (called εἰρεσιώναι) bound with wool and decorated with small symbols of prosperity, like small bottle of oil, dried fruit, figs, coins, etc. In the Orphic tradition, we celebrate this holiday always on the 20th and 21st of May.

v. Carnia/Pyanepsia: late summer/early autumn festival of Apollo (the Carnia is Doric, while the Pyanepsia is Attic). Both of these have additional significance that is unrelated to either the harvest and plowing or to Apollo, which are the major practical and religious associations of these holidays. The general themes of these is to explain the rather odd names of these festivals — 'Carnia' seems to mean 'ram festival', and this might be a reference to Apollo's being depicted with ram's horns at the Carnia, but the Dorians tried to link the name to various mythical characters named 'Karnos' or to a plant by a similar name which someone had damaged and thus angered Apollo. 'Pyanepsia' means, 'bean boiling', and was interpreted by the Athenians to be a reference to the hero Theseus' dining on a meal of simple cooked beans after returning from slaying the minotaur in Crete. However, in practice, both of these festivals are, practically, summer harvest/fall planting festivals, and religiously, times of devotion to Apollo. The Pyanepsia was celebrated around early October, while in the Pelopponesian Orphic tradition, we celebrate the Carnia any time between the full moon of August and the full moon of September.

vii. Nativity of the Sun: this was probably originally a Persian or near eastern festival. Celebrated on the 21st of December, the longest night of the year, it is considered the birthday of any of various popular solar deities. It is first a somber occasion during the longest night, while the dawn the following day is a joyous occasion, marking the return of lengthening days and the blessings of God. It was one of the most popular festivals in Antiquity, and remains very popular. It remains celebrated in Iran today as well, called Yalda Night, or Shab-e-Yalda.

viii. Winter Bacchanalia: celebrated in late December by the Roman calendar, it is a bacchanal festival that, historically, had often been blended into the Solar Nativity because of their closeness in the calendar. It is directly equivalent to the Roman Brumalia, and equivalent in time and much of its practice to the Saturnalia. It is a longer festival, lasting for about a week or more, depending on the tradition. In modern Orphic practice, it is taken as primarily a bacchic festival, but is extended, over the course of its twelve days as we celebrate it, to a festival of all the Gods.

Beyond these, each month is sacred to a particular deity, as is each day of the week, and even each hour of the day, and dates for special personal worship are traditionally scheduled at the most auspicious time possible for the occasion, by following some or all of these time associations.

Likewise, the equinoxes and solstices are considered very auspicious (in Orphism, the autumnal equinox especially), as are the new moon days. However, these are simply holy times, and are not really specific holidays.

There is more to it than this, and you can certainly spend a lifetime learning about the various classical festivals (virtually every day of the year was some sort of festival), but I think this should give you a good start.