AOL Reader is, for me, emerging as the best replacement feed reader atm and here's why.
The interface is modern, flat and rather OS X like. The main theme differs through various shades of blue. Though there is a "Light" version you can switch to, all this does is alter the overly large header bar to use a white background instead of dark blue. Speaking of, the header bar is childishly large and overbearing and also seemingly useless. The search bar opens a new tab and searches the wider web using search.aol.com rather than searching the feeds, I can only imagine this is purely temporary as most replacement services seem to be struggling or at least leaving "search within feeds" features till the last. On the right hand side of the header bar are a series of large icons shamelessly plugging other AOL services such as AOL On and AOL Mail.
Above: The AOL Reader Header bar.
The business model AOL have opted for is ad supported, though I use AdBlock so I cannot comment on the content (whether it is inappropriate or mines the content of your feeds). It does mean that though I block out the ads, that doesn't negate the space they use, so a good inch or two is wasted on completely empty space that could be well served in some of the layout styles. (There are userstyles and Chrome extensions that purport to solve this but I didn't have any success with the one I tried - https://chrome.google.com/webstore/detai...).
Above: The unfortunate wasted ad space, empty thanks to adblock.
The "Add Subscription" feature isn't as robust as the likes of Feedly, it doesn't have as many site feeds included in it's ready-made offerings and the search won't always find obscure RSS feeds, meaning some footwork and manual labour is required to find the addresses and add them. The process overall remains fairly simple though, especially as they offer importing of feeds from OPML files (note that if you joined Feedly after they enabled their own cloud and can't export from Google Reader any longer, annoyingly the OPML Feedly gives you seems to be extremely broken and is hopeless when imported. Though AOL doesn't even offer the option to export at all yet).
Above: The add subscription menu, with categories at the bottom that advertise popular feeds.
Below: Searching for a feed.
The layouts include:
List - Your standard Google Reader style list, with a bookmarking button and site names on the far left, titles in the middle with a little snippet of the first line fading out to the right where the time and date it came in overrides it.
Above: List view collapsed.
Below: With an item expanded.
Card - Similar to Feedly with cards for each item containing the title, a snippet, a thumbnail, the date, bookmarking and mark-as-read as well as sharing buttons. Of note though, is the fact that despite having the space this view seemed to stick to a two card width which is bafflingly awkward.
Above: Card view collapsed, limited to two cards wide.
Below: With an item expanded.
Full - A very handsome full view that expands all posts. Marking as read as you scroll can be turned on in the settings.
Pane - My favourite is the pane view which creates a three-pane layout more common in desktop-based feed readers and imo is the killer feature that sucked me in to this service. It's a little crippled by the childishly large design, meaning bolded titles in a large font barely fit in the boxes and often fade out beyond the bounds of the box meaning you are completely unable to see the snippet that is hiding there. I'm overly critical as it's my favourite view but it functions better than any of the others for my reading style and AOL has done very well by it.
The sharing options are much more social, meaning as yet there's no integration with services like Instapaper and Pocket, but the staple social ones that are often strangely lacking in other services are there; with Facebook, Twitter, LinkedIn, Google+ and an email option.
Overall, this is my favourite Google Reader replacement. With lot's of my previous go to services unfortunately beginning to charge or ramp up the freemium options. Feedly is the main competitor (though I fear it has already won), but with it's seemingly purposefully crippled OPML export, its recent growing lack of speed and it's almost transparent interface and palette that leads to misclicks (or quite often; me having to awkwardly angle my head or monitor to gain a bad viewing angle to increase the visibility), I feel that Feedly may be unprepared and simply riding the crest of a wave that might crash any time now.
AOL Reader is now available in beta requiring a sign up via an AOL, Facebook, Google, or Twitter account. You should then be emailed an invite shortly after. It's well worth the try.
UPDATE: I am finding that site feeds that were fully fledged in Feedly, meaning I'd see the whole post without a jump break and all images/thumbnails, are coming up short in AOL Reader as well as in Digg Reader. It appears they only drag a few lines from a fair few sites.
As a result I've been using this and Feedly alongside each other, with Feedly slowly clawing it's way back on top.