I've never played sandbox, buy my understanding is that it is just like the campaign without the main quest. These are the benefits of the campaign:
Early game you get two brothers and a sister - they make excellent party leaders or governors and you can get $50k for marrying off the sister and more clan members and offspring if you marry off the brothers (and set them up to be in the same place as their wives)
Mid game you get a steady stream of mid-tier quests (the conspiracy quests) which can give you cash and experience at a time when you might need it - a lot of people hate these and I mostly ignore them
Late game you get massive extended war with three major enemies - are you tired of being at peace too much? Now you can't make peace - you have to decimate each of these three enemies (usually taking them down to about half their original size)
Post victory if you play Empire, the other Empire factions join you with all their fiefs and you can keep playing as the united Calradian Empire.
If you only want the siblings and don't want to deal with the conspiracy quests or the three wars, you can play campaign and do the first bit but stop before you assemble the dragon banner.
Victory in 1094 as part of the Southern Empire - level 29 tier 5
This is only in campaign mode?
Yeah - completing the main quest in the campaign
Nice! Would you recommend campaign over sandbox these days? I haven't played the campaign in quite a while because it was rather incomplete back then.
I've never played sandbox, buy my understanding is that it is just like the campaign without the main quest. These are the benefits of the campaign:
Post victory if you play Empire, the other Empire factions join you with all their fiefs and you can keep playing as the united Calradian Empire.
If you only want the siblings and don't want to deal with the conspiracy quests or the three wars, you can play campaign and do the first bit but stop before you assemble the dragon banner.