IMHO guilds should be a source of quests, guidance, companionship, and/or profit for the players, depending on the nature of the guild, but the trend that we had in Morrowind and Oblivion that in each guild that you could join, the quest-line set a path for you to finally become the leader of that guild is not what I call an inspired game design.
Each guild should have its setting and situation that would most probably differ from other guilds and for most of the guilds, the quests should not be designed in a way to end in your becoming the guild's leader, so for instance:
Guild A:
There is a corrupt leader that is leading the guild to its doom or complete corruption, you offer to join and for instance you are told that you have to pay 300 gold to enter, and when you pay the fee and enter that guild, you are given jobs that feel a bit fishy, for instance you are told to go for a night mission and destroy a farm at the side of village and kill the cattle there, or you are told to go and hide in a narrow valley, outside the town and stop a caravan from entering the town by any means, and so on...
And when you ask them why you should do those actions, you are given seemingly valid reasons so that you are convinced that you should do the job, but there are some members of the guild that do not like the way that the guild is heading, and are plotting a revolt, and after you have completed some of those tasks, they approach you to say that the tasks were given to you just for the profit of the guild's high level members.
And you were send to damage the carriers of the people who opposed those high level members, and the guild's original quest was quite different from what is happening nowadays, so they ask you help them find out facts about those high level members that could help them in their current quest of eliminating their power in the society and the guild, and so on...
You have the option to work for both sides and profit from the masters, and help the lower level members with their quests until they could accomplish their mission and overthrow the guilds leadership and become a trusted and ranked member of the new guild, or you could side by masters only and tell them about the plot and eliminate the plotting lower rank members and become a trusted and ranked member of the current corrupt guild.
After that either you do your corrupted jobs with more profit, or you do the original guild's untainted quests and get the other type of rewards.
Guild B, Guild C:
There can be two rival feudal houses in an area of the province that compete with each other to become the upper-hand power in that society, and you could join each house or both, and you could work for both for a while until some later missions that would force you to decide to lose a house's trust and standing to be able to gain more trust and standing in the other.
You cannot finally become a monarch, but you could gain a monarch's trust and become close to him/her.
Guild D:
There can be a guild that has lost their leader recently and they are at total mayhem, because of the rivalry of two opposing sides within the guild, and the resulting conflicts, they do not accept new members for now, but you could befriend some guild members on any side, and gain your membership, and after that you could gradually gain the trust of both sides and pretend to try to help each side, but you could complete the jobs in your own way, so that finally with some tricks, intrigues, and blackmails you could snatch the leadership in front of their dumb noses.
Guild E:
There can be a merchant guild that have lost some caravans recently and need help to solve the problems, and you could join and help them, and with each gain of status, you could have better barter deals with the members of that guild.
OK, enough plots for now, and these examples show what I meant.