For Independence:
Decisions about Scotland should be made by Scottish citizens
Scottish taxation and spending would make them a more successful country
Scotland could focus on Scottish issues and priorities
Scotland would not have to fight British wars or be home to Trident (Nuclear Weapons System)
Scotland has an ageing population and could more easily encourage economic migrants
Scotland could still have a good relationship with the UK but on an equal footing
Against independence:
The UK has won wars, built an empire, and been a successful union for 300 years
Being part of the UK means being part of the EU and single market
Businesses could move their established bases to somewhere else in the UK, leading to a loss of Scottish jobs due to new taxes and regulations
Scotland would need to establish a currency union to continue to use the pound
The UK is an influential member of international organisations like NATO and the UN. Scotland would be less influential
Joint security across the UK is better