Help us decide on a route

Me and my friend are planning to visit europe this summer and it will be our first trip without our parents. we're looking for a trip route in which we can see at least 3 cities and we're planning a week long trip in July. we're students and we have a limited budget so we're looking for an affordable route as it's gonna be our first.

we have discussed a few routes till now which are:

• Prague-Vienna-Budapest it's a quite good route yet we don't know if it's the best
• Lisbon-Porto-Madrid we're just afraid of the weather bc Mediterranean cities are very hot during July
• Rome for 5-6 days my friend recommended me this one but I don't want to stay in a singular city all vacation. also I think Rome is probably beautiful if you have a good budget
• Kopenhagen- Bergen- Oslo- Stockholm I think Scandinavia in summer is the best time to see there but still not sure if it's the best option
• St. petersburg-helsinki-stockholm not sure about going to Russia 😬 but st. petersburg is very beautiful so maybe yes

so these are the options we thought of. if you have seen any of these routes which one do you recommend? or do yall have other recommendations rather than these?