Buffs can be pretty 1 sided in games, but there should be buffs relating to what you are doing or have achieved for example...
Personal buff like Lucas Arts SWBF2, have your own buffs that only affect you.
Relating to ember, once you achieve a state of an achievement you'll retain that buff like a rank. Reference.. Check it out:
http://battlefront.wikia.com/wiki/Awards
I dont like guild exclusive buffs however, a stackable Aura buff 'may' help this topic.
But, I do believe there should be guild achievement based rewards. Refering to this link:
https://wiki.plarium.com/index.php?title=TD_Clan_Achievement
The buffs should not be giant buffs.
Adding to this, personal and guild buffs
Have categories like general, combat, economy etc. Both share some of the same perks, guild achievement perks are a lot harder to obtain though, eg: (keep in mind they are both achievement based)
Economy - Refinery speed:
Personal: Rank 1: +10%
Guild: Rank 1: +12%
From the guild your personal buff will be overided adding an extra 2% as a bonus to guild teamwork from an achievement reward vice verca (whatever is the highest) eg:
guild refine 1,000/+ azurite 10,000 times.
Rewards at max rank:
Economy - Refinery speed:
Personal: Rank 10 (Max): +60%
Guild: Rank 10 (Max): +85%
(stats variable dont freak out lol)
IMO this is a fair way to reward an indervidial solo player and guilds.
Noting that guild achievements are way harder to obtain and adds guild loyalty than 'clan hoppers'.
Hope this can help