2 things that come to mind for me - and bare in mind I only play the largest possible maps with the max number of civs...
The first is that Sumeria's barb bonus works well with the science boost from ziggurats. I don't play many games where camps are not ever present even as late as the industrial age, and assuming camps can still respawn, it would be fairly easy to assure that some do... even if it means dowing.
The second is pillaging and how it meshes with civ bonuses. While taking a well fortified city may be a nightmare... simply pillaging not only cripples civs, it provides a boost to the pillager as well. Sumeria, Rome, and civs with worker boosts will shine under this system.
Most of the civs, if not all, have a way to shine. But, to me, Germany, Rome, and Sumeria look to be able to prod buttock under any conditions and against any opponent, with Germany having the slowest ramp up but highest potential. As culture is now a second science tree, both Rome and Sumeria offer crazy 'tech' boosts that may be impossible for the ai to catch up to.
That said, I don't really care about how strong a civ is... I am going to play what I want and make it the strongest. I haven't seen a civ yet that looks unexciting to play - an awesome change from V. Kudos to the dev team.