If you are new to a game, you do not know its mechanics. Beeing forced to choose an option from the beginning may only lead to a high dissatisfaction and a player may (if he is patient) restart the game again with the other choice that is more his playing style.
Well or he simply quits because he is constantly and it is always begging in his mind 'you made the wrong choice, you are bad, you could be better, but you aren't'. - Which would be only a time until he drops that game.
I did choose Option 2 because someone should only make a 1-time-choice of a new mechanic 'after' he learned the game. But I would add here the option to change, it, too, if he is too unsatisfied.
(Drifting away to a fraction system:)
This reminds me kinda of 'Hands of War', which is a singleplayer 2D flashgame, in which there are at least 6, probably more frractions hating each other. Well one fraction do not hate all other ones, they only hate their personal enemy like the thieves and merchants hate eachother, the guardians and the assassins hate eachother and there is one speciality case: the archers, knights and mages hate all eachother.
Though e.g. Knights are neutral to guardians, assasins, merchants and thieves.
So you have to make choices in that game: All fractions start neutral and you barely see any quests you can get from anyone. Then you start killing people from one fraction, which will be your first decision. 2 kills of either thieves or merchants unlocks the first quest of the fraction you did help by that. By finishing that quest you gain even more repetition in that fraction and naturally harm the enemies of that fraction, making it almost and at a certain point completely impossible to turn back to the enemy fraction.
(Drifting back to topic)
Well, I like a fraction system, but I would like the chance to turn back, too. So in Onyx this could be that there is a quest that is always accessible and which is also repeatable (kill x respawning cybersheeps, that invade our farmlands or: we are low on resources, support our cause and spend 20 potatoes). In best case a quest that will not actually harm the enemy fraction. Later on however, there will be better quest that will grant higher reputation but fulfilling this will decrease the reputation of the enemy fraction more than it increased the one you helped, forcing a player to concentrate on one fraction.
Well, I like to see many fractions I can choose at once, but if it is really necessary to choose between fractions, then you can make a critical choice if you gained enough repetition in one fraction. You will then be an 'elite member' of said fraction that will automatically remove even the 'potatoe'-quest from the other fraction.
I think about the chance to abandone your title. Which would degrade you to the position in your fraction you had before accepting the elite rank. This will also decrease the maximum gainable fraction points back to what a non-elite-member can have again and literally make fraction-exclusive stuff that need more fraction points inaccessible.
(On topic again: comprehension:)
Back to topic: I like to make a decision later, but nothing should be punched in stone.