I own a FN SCAR 17S. The recoil isn't that bad at all. And that's due to the same reason that it produces a pretty strong muzzle blast: it uses a PWS FSC30 muzzle device.
http://primaryweapons.com/muzzledevices/fsc/
It's still my favorite firearm. However, the Tavor has converted me into a bullpup advocate. Bullpups are so much more comfortable to use in my opinion. Wikipedia claims that IWI is working on a Micro Tavor chambered in 7.62 NATO. But if you don't feel like waiting for it to possibly come to American gun stores some day, then you should check out an AR-10 or a VEPR.
These are my two favorite AR-10s:
http://www.dpmsinc.com/308-ORACLE-ATACS_ep_98-1.html
http://www.smith-wesson.com/webapp/wcs/stores/servlet/Product4_750001_750051_815078_-1_785153_757785_757784_ProductDisplayErrorView_Y
VEPRs:
http://www.atlanticfirearms.com/component/virtuemart/shipping-rifles/vepr-ak-rifle-tactical-308-russian-16-5-detail.html?Itemid=0
http://www.atlanticfirearms.com/component/virtuemart/shipping-rifles/vepr-308-rifle-md2-detail.html?Itemid=0
As to AKs, I recommend an Arsenal:
http://www.atlanticfirearms.com/component/virtuemart/shipping-rifles/arsenal-slr107fr-31-762x39-side-folding-rifle-detail.html?Itemid=0
You also didn't really explain why you're trying to decide between the two rounds. If you're worried about stopping power, then the 5.56 and 7.62x39 are pretty comparable.
http://www.ballistics101.com/223_remington.php
http://www.ballistics101.com/7.62x39.php
The 7.62x51/.308 is however a major upgrade in stopping power:
http://www.ballistics101.com/308_winchester.php
However, a good .223/5.56 bullet is still extremely devastating:
https://www.youtube.com/watch?v=Msci2ciZ4yo
If you're worried about long range accuracy, then the .308 is definitely the way to go. It does a much better job of resisting the influence of wind.