Which do you think is better for theming Panels or Display Suite?
About the same, however it's rarely an OR question, I tend to use them together - Panels/Page Manager for the page layouts, and DS for node layouts.
DS beats Panelizer IMO because DS can theme view modes, like the teaser. However, I havent used Panlize enough to really know its power in other areas. I simply prefer DS and keep using it.
With regards to styling either, same same just different.
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