Good night,
Greetings from Venezuela, from here full support and affection for the project.
Well, my opinion is that this is a delicate and complex point that can take a long time to discuss and reach an agreement, however I will try to give my best opinion on it.
First of all I have to say that I have played several but it is that many games where talents are an important part of the construction of the character, for example, Allods Online, Path of Exile, World of Warcraft and in all of them I have seen good things and bad things.
Among the good things is that if the user is given a large branch of talents to choose from to customize and make a class to their preference and taste, they will feel a feeling of progression and unique customization, since it will give the feeling that they have a unique character. and different from any other player.
And one of the bad points is that, for example, if this great branch of talents is not carefully worked at the time of the passives and bonuses that it provides to the classes, it can trigger broken classes that stand out and are far superior to others, causing their You see a chain of imbalance in PVE and PVP.
Therefore, my suggestion is to take the best of each of the aforementioned exponents and others that I do not list, but making it friendly, controlled and easy to understand but at the same time loaded with diversity. For example:
They can place within each class branches, that is, if you are Paladin, within it is the Paladin Healer, Paladin Tank or Paladin DPS, after your choice you will have at your disposal as a player a book which will be divided into two pages or tabs, one called Skills and the other Specializations.
In the Skills page or tab, you will find Lines of Skill Tiers that you will unlock and select according to your preference, that is, you will have the first line of skills at level 10 and in it there will be three skills and you must choose one of them only, then At level 15 the second line of skills will be unlocked and you will have to select again one of the three skills offered, and so on until you reach level 50 (I propose this level considering that this is the maximum at the time of the official start of the game). It should be noted that these skills are dictated according to the branch chosen above, be it Healer, Tank or DPS.
Then to feed the progression of the character and provide the player with a much greater advancement and satisfaction system aiming above all at the END GAME, when your character reaches the maximum level in this case level 50 this Specialization tab will be unlocked in which upon entering you will see a A huge tree of talents that depending on the chosen branch is Healer, Tank or DPS will allow you through a large number of small passive bonuses to enhance various offensive or defensive stats of your character and role. Additionally, allow you to enhance the skills previously chosen in the Skills tab, so that they become an evolved version of the previous one. All this controlled by an experience bar system and limited specialization levels, example, the limit is 100 specialization levels, which when leveling up will give you points of specialization that you will invest in the talent tree, said experience that can be obtained by doing various activities, for example, Battlegrounds, Arenas, Dungeons, Raids, Events, etc.
That would be my suggestion.
You are very detailed in your posts, that is awesome :)
As for the progression after level 50 like a mastery system, I totally agree that it will bring more end game content and keep players grinding their way to greatness. Also, bring more diversity in the class builds.