There is no comparison between Civic and Sonata but just a drive compare of both.
I test drove Civic oriel test unit and Hyundai Sonata2.5. Drive of Civic is much more sporty and Sonata cant match to its acceleration. Sonata (2.5 version) is not under-powered at all as well with luxurious feel drive.
It is all about personal preference and happiness of a person about choice between both.