Apple CEO Tim Cook speaks about the new iPhone during an Apple product announcement at the Apple campus on Sept. 10, 2013 in Cupertino, Calif. (Justin Sullivan/Getty Images)

Ad-blockers are all the rage on the App Store, thanks to a new feature in Apple's iOS 9 operating system that lets users download apps that strip the Web of advertisements. There are quite a few options, so we took a quick look at how some of the top contenders stack up.

Before we get into the nitty-gritty comparisons, it's worth mentioning that there's a lot of controversy around these apps. From a consumer standpoint, it seems like a good deal — particularly on a smartphone, where even a small ad can take up a lot of screen space. Ditching ads makes sites load faster and easier to read. And blocking tracking software may give those worried about privacy some peace of mind.

The flip side of that, of course, is that the site you’re reading is using that annoying ad to pay its bills or (gasp!) to turn a small profit. And not every site has the capability to run elegantly designed ads. A recent report from analysts at UBS estimated that ad-blockers will cost publishers just $1 billion. That's a drop in the bucket for the industry, but the analysts added that the burden may hit some sites harder than others, depending on their audience. (Generally speaking, the tech-savvier the audience, the more it will hurt, since techier readers will know how to install blockers.)

So you have to think: are the negative aspects of ads enough to drive you to cut off the revenue for the site you’re viewing, probably for free? Weighing that question pushed one top app developer, Marco Arment, to pull his top-selling ad blocker from the App Store recently saying it "just doesn't feel good."

Yet even consumers who have thought about those repercussions have their justifications for downloading these programs. Check out the reviews of blockers on the App Store, and you'll see well-reasoned debate about the state of modern advertising — the words “obnoxious,” “intrusive,’ “abusive” and “tracking” feature prominently.

Ad-blockers give consumers more choice, but it is a choice with a consequence. Remember, too, that it doesn't have to be black and white: some ad-blockers also give you the option to “whitelist” certain sites, essentially letting you vote with your eyeballs to say, “I like this site enough to put up with its ads.”

Okay, the preaching is over. Let's talk software.

The process of installing an ad-blocker isn’t difficult, but it’s not exactly a cakewalk either. You have to download a separate app, and then fiddle with your Safari settings (Settings > Safari > Content Blockers) to allow the ad-blocker to do its thing. Also, remember that these blockers only work for ads on the Web. That means it won't work in apps, where Americans spend nearly 90 percent of their time.

All blockers are also not created equal. Some are one-size-fits-all, others allow for a little more customization.  Worried about ad-tracking? Block those trackers. Slow page loads got you down? Kill some of the photos, videos and fonts. Hate everything? Block all of it.

Crystal: This is a very simple ad-blocker. It has one setting — on or off — and blocks advertisements, as promised.  The all-or-nothing approach does, however, have its limits. Occasionally while browsing, I came across a site that wouldn't load with the blocker on, sending me into my Settings app to toggle the blocker off at least a few times per day, particularly on shopping sites, but also on notable media sites.

If you come across a site that doesn't work or an ad slips through the cracks, you can report it to the company via the app or the Safari menu bar, but there is no whitelisting. 99 cents.

Purify Blocker: Purify is one of the more expensive blockers, but it also offers quite a bit of customization. It lets you block ads and trackers, of course. You can also choose to block images, scripts and fonts — all of which can help your load times and keep down your data use. Doing so can make sites look a little wonky, and you can occasionally block legitimate content by accident. Still, it's nice to have the option, particularly if you're somewhere with a bad connection.

Purify also lets you add sites to a whitelist from within Safari, which is easy to do mid-browsing session. Not having to jump back over to the app or to the settings menu is a small but important convenience. $4.99.

1Blocker: 1Blocker's app is a free, simple and powerful ad blocker that noticeably cuts down load times. Sometimes that means blocking more than you want — like the actual article or photo you're looking for, but it completely depends on the Web site. 1Blocker also lets you get rid of things, such as social widgets, some comment sections and ad trackers, but you have to pay to block more than one type of thing at a time.

There's no whitelist, either, so the same settings will apply to whatever you're browsing. It's free, with the option for a $2.99 upgrade.

Blockr: Blockr gives you the option to block four things: ads, media, trackers and those warnings about cookie policies that pop up all over the Web. You can even mix and match by site, if you want. Each of those trackers has its own whitelist, so you can really fine-tune your browsing within Safari. So if you find content from a site you frequent gets tripped up in a filter, or you don't mind its ads, you can selectively turn that off.

Overall, this is some thoughtful design, particularly for those who struggle with the ethics of blockers. In fact, the developers even note in in their tutorial that, “Many websites live from specific content they present to you. It’s not our intention to cut this support. We want you to choose.” 99 cents.