But I understand many people have been leaving because of the high taxes.
I'm sure some people have, but more people are coming in than going out because there is still plenty of opportunity here. Honestly I've never really thought of the taxes here as particularly high - gas is noticeably more expensive in part due to high taxes, and cigarettes, but certainly not worth moving away over. All kinds of things vary widely from place to place though - for instance I'll be spending quite a bit less on rent when I move, but electricity & gas suddenly become a much bigger factor if you're in a state that has seasons, something I've never really had to worry about living along the west coast where the temps don't vary much.
As a general rule, places that are more expensive to live in also feature jobs that pay more. Most people who live in the sticks don't make shit.
The ratio between cost of living and incomes varies widely though, and it's currently worse in CA than a lot of other states. This is an interesting example:
http://www.interest.com/mortgage/news/big-city-housing-less-affordable/
So they're just looking at affordability of housing, but it gives a good snapshot - unfortunately it's getting worse across the board, but more so in CA than elsewhere. 4 of the 13 'failing' grade cities (and 3 of the 5 "F" grades) are from CA, none of the 12 'passing' cities are. Even though there are generally higher median incomes in the CA cities, the property values have just outpaced them in recent years.
We're moving from SF to Philly, which is one of the 'passing' cities - although barely so (C-). But the median home price there is 1/3 of SF's, while the median income is 80% of SF - that makes for a massive difference in terms of how affordable it is. LA and San Diego have nearly the same median income as Philly, but median house prices are 40-50% higher - still a huge difference.
So I'd say it's worth considering if you're planning on moving to a big city in CA - you'll probably need to be making well above the median income to really be able to afford to live there. Otherwise you end up living well outside the city and making an hour+ commute each way every day, which is how a lot of people do it here.