The O's just declined their half of the option they held on Nick Markakis, so add him to the list of potential OFers the Braves should target. Assuming he isn't offered a QO (and it doesn't look like he will be since the O's declined his $17M option in favor of a $2M buyout), his career .358 OBP (.364 vs RHers, .344 vs LHers) would look pretty good at the top of the Braves lineup.
He will probably end up being too expensive for the Braves budget (~3yr/$40M), but a top 5 of Heyward, Markakis, Justin, Freddie, and Gattis would be a nice start. I would expect Aoki to put up very similar OBP to Markakis over the next 2-3 years and be much cheaper (by over half), so I would rather see the Braves target him instead.
As it currently stands, I would rank my preferences on OFers based on cost/performance as:
1. Aoki
2. Fowler
3. Markakis
4. Hunter
5. Rios (he would have to come cheap to even be an option though)