I will actually second this. Wipr is really good.

Also, generally speaking, the way Safari implements this means that the extension passes on the block list to the browser and Safari itself implements the blocking. This means,

1. It is more private since the extension does not have access to your webpage. 2. It is faster because Safari can do it natively and it is not done in JavaScript.

YMMV (probably depends on the subset of the web that one visits) but I've had good luck with Wipr under Safari. Once in a while something slips through but it's generally ~99% as effective as uBO when it comes to visible ads. The difference is small enough that I'm not inclined to use a different browser.