Given just 4 days which major city in Scotland would be the best to visit
There are only 8 cities in Scotland. Most people would put Edinburgh and Glasgow top of the list.
Well I'd say Edinburgh, having been there twice and loving it. But I've haven't been to Glasgow, so I can't compare.
Putting it another way, where will you have come from, and what are you interested in?
For normal city things like history, art, museums, culture and the like, I would suggest Edinburgh.
If you were looking to see more of the islands and lower Highlands, rather than the city, I'd say Glasgow.
If your interest is the northern Highlands, then I would say Inverness.
I've been to each of these cities numerous times.
Glasgow has got it's fair share of culture and museums, such as https://burrellcollection.com/ and https://www.glasgowlife.org.uk/museums/venues/riverside-museum and https://www.citycentremuraltrail.co.uk/murals/muralabout/79
but some perspective on geography and travel might be useful. Glasgow and Edinburgh are less than 50 miles apart centre to centre, there is a fast train from Glasgow Queen Street station (main concourse) to Edinburgh every 15 minutes (every 30 minutes on Sundays) which only take around 45 minutes end to end. In some big cities in other countries you could travel 45 minutes between attractions without leaving the city. So it's very possible to stay in one of the two and have a day in the other. Be aware that Edinburgh is very busy in August (busy= hotels full and expensive)
Personally, we liked Glasgow more than Edinburgh, likely because it had more of a city feel to it whereas Edinburgh had more of a tourist feel. But we loved both. Whichever you choose, I would recommend a daytrip to Stirling. That was our favourite day in our 2 week trip. We enjoyed Stirling Castle far more than Edinburgh Castle.
Personally, we liked Glasgow more than Edinburgh, likely because it had more of a city feel to it whereas Edinburgh had more of a tourist feel. But we loved both.
I mostly agree with Allan. I wouldn't go so far as to say I liked Glasgow more, but walking around in Glasgow and riding the fun, quirky underground (it's a single line that goes in a loop, so you can get where you are going in either direction) are a joy. Glasgow also has great museums, most particularly the Kelvingrove, a large and fascinating collection of art, artifacts, and so much more.
But Edinburgh is prettier, more charming, and filled with interesting museums and other sights. Though I have to say I think Edinburgh Castle is highly overrated, and the crowds made it altogether unpleasant for me.
If you're only going to one place in Scotland, I would choose Edinburgh.
If you're seeing more of the country, then I agree with Glasgow for easier access to the Highlands and Islands.
With your limited time, Edinburgh is my suggestion. Been there several times and have yet to see it all.
Since the OP didn’t come back and since we will be visiting both cities in two weeks (Yay!), I will say thank you to everyone for taking the time for their comments.