Depends on what youre into, but the livliest of cities in terms of night life has to be Zurich.
I hope you have a successful move and enjoy your stay here.
One thing I keep meaning to ask is what is a gene van? It is in your signature, and maybe you need to be a Genevan, someone from Geneva?
Can't make a comparison between Zürich and Lausanne. Some others might have opinions.
What are you going to do here as a self employed man? Conditions are quite difficult here, you can't just start work as a builder, you have to be qualified and have finished a recognised apprenticeship. You can't start a company, you have to be a qualified "Master of your Trade" Have you found out about working life here?
OP, my advise would be either Zurich or Basel with Zurich having the edge considering you are coming from a world city like London.
If you love London life , Zurich will come as a shock. Whilst many cultures live here - the diversity is limited. Do not expect a buzz like London or any other major European city. TBH that has more to do with the mentality that the facilities here - ZH may not be deathly dull but it is in a different league. It's a great city to bring up young children safely !!
There are other cities that you should look at first - Barcelona, Berlin etc but most will be affected by the very similar taxation throughout Europe. New York ? Sydney? Hong Kong?
You location will depend on what you do - can you get a work permit for here?
If you are a die hard MTBer of powderhound that CH has a lot to offer - but so would Italy, France and Austria
You seem to have decided on ZH, or has it been decided for you?... have you been here or spent any time here?
EDIT: = Other in the poll, as it makes no difference where you end up: it won't be the same as London, and you can't take London with you.
Anyway, you're self employed and think cost of living isn't a problem so I assume you aren't a painter and decorator. Let's say you're a magically profitable day trader who, as they're all convinced is the case, will be consistently profitable for the next 20 years. For argument's sake let's say you net £1M per year. Guess what? Cost of living will still kill you? There are a million threads that ask if it's possible to live on 120k. The only answer should be, "not like you can in London mate, unless your interests magically change from dining out and theatre to hiking and biking overnight".
The other thing is that taxes here aren't really lower if you live in anything larger than a hamlet. They just seem lower. Taking everything into account (I live in 8001 Zurich, the absolute best area for young people in Switzerland- since you asked) I don't think I net out any more than if I lived in London, except the cost of living for me is roughly 2.2x what it is in London (I calculated this recently based on my lifestyle).
And finally, you live in Soho I assume by choice. By comparison, I'm afraid there aren't any good places for young people. Your thread title say it all really - Best Swiss City. There aren't any that you'd recognise as being cities at all. Now close your eyes and imagine that you live in the same apartment that you do now, but it costs flat double. Imagine that you live, not in a city of 7 million, but a town of 250 000 (Zurich). Imagine you walk into Pizza Express and on looking at the menu you find that the cheapest margherita pizza is now £20 and other items just go up from there.
In my opinion, going by your post, your making a massive mistake moving to Switzerland. You haven't discovered anything new. Everyone in London knows where Switzerland is located and almost all of them stump up the tax because it's worth it. And this includes almost every banker and almost every millionaire. You get what you pay for. You get to live in a world city, a cosmopolitan maelstrom and....bah, you're only 22, this is the kind of nonsense I used to come out with at 22 as well.
When it comes to socialising and night life, Zurich beats all other cities hands down. You'll meet a lot of diversed cultures and ofcourse the english speaking lot are in abundance.
Wish you a good one.
Cheers,