Positive benefits of staying in UK:
continued membership of many internationally renowned organisations/regulatory bodies etc
continued advantages of sharing the same landmass/coastline
continued added value of having a large, prestigious city as capital
continued experience of having a long-established democratic political system
continued shared established currency
continued international influence
continued membership of the EU (as a long established member we don't have to negotiate everything)
continued 'friendship' with America (maybe a mixed blessing)
Disadvantages of setting up as an independent country regardless of the rights and wrongs of the idea of self-determination and regardless of the actions of rUK or situation peculiar to Scotland/rUK
a new border will be created
need to negotiate with a different country - likely to result in new grievances and even if it doesn't, a huge cost in time, human resources and money - surely that effort could be better spent on constructive projects
Scotland would be a country that dismantled an existing longstanding partnership despite the rest of the partnership not having a say
Unless there is a huge majority yes vote, a very substantial portion of the electorate will be very unhappy about being separated from the rest of their country; not a good basis for a new start
Scotland will be working for what is best for Scotland, regardless of what is best for the whole of Britain. You may claim that Westminster has done that in the past - but that doesn't make it acceptable for Scottish politicians to act in the very same way they criticise other politicians for.