I downloaded Purify ($3.99), 1Blocker (free and the $2.99 pro version) and Blockr ($.99). Of the three, I much prefer Purify. Pages loaded the fastest with Purify over the others. Purify also has a whitelist feature. The second best is 1Blocker, but, on average, pages load somewhat slower than Purify. Also, some pages were broken and you cannot whitelist them under 1Blocker. Coming in third is Blockr, which loads the pages the slowest of the three and let a couple of ads slip by.
All do the job and I'd take any one of them over having no content blocker. The ads were becoming so ridiculous that it took away some enjoyment from using Safari on my iPhone6 and iPad Air. It comes down to a matter of preference and Purify is my favorite. Now web browsing is fast and there are no more annoying ads! Just make sure to whitelist such sites as YouTube if, for example, you want to watch YouTube videos on Safari. It's simple and straightforward to do.