Irish people are more welcoming than Brits.
That's a bit of a myth really. Irish people are more superficially friendly in that they're very relaxed and will chat easily with strangers but it's hard to get beyond the casual acquaintance stage with the Irish.
Cork for example looks similar to San Francisco in a way
You mean it looks physically like San Francisco?? Don't see the similarity myself. It's a good place to be if you're very into cultural things like ballet, opera, art, music but the city itself is not the friendliest place. Cork people are considered quite 'clannish'.
It's quite hard to find a job in Ireland outside of Dublin. If you work in Galway or Cork and lose your job, it can be a struggle to find another. Also the cost of living, particularly rent is very high and outside Dublin public transport is almost non-existent.
Now having said all that, there are plenty of people who move to Ireland and are very happy there, but whatever country you're considering you really need to do your research first.
You mention Prague - if you're Czech, you might find it easiest to adapt to Poland and it's not too far from home. You could give it a try for a year or so.