So, I think time and place are important considerations in the comparisons of these figures.
Direct comparisons are going to favor the originals pretty much in every regard. The Classics versions came during perhaps the single best period of Transformers engineering ever. Not only did the Classics versions hit the old design cues, they added the update "flare" of the line while implementing groundbreaking articulation for Transformers without sacrificing or resorting to ball-joints.
Mirage by
ME_Counterpunch, on Flickr
Mirage is still an outstanding figure and is a slick update to modern F1 race cars.
Sunstreaker and Sideswipe by
ME_Counterpunch, on Flickr
Sunstreaker epitomizes what was good about the initial Classics figures. Characterful, clever, well proportioned, and so well done that no 3rd party company even bothered to take a stab at him in the Classics scale.
Prowl by
ME_Counterpunch, on Flickr
Prowl is frankly a little less inspired as his mold and mold brothers have a few issues that could have been improved upon, but he does the difficult task of replicating the car chest look without being terribly awkward.
All that being said, I think the current offerings are updates to the characters just as the Classics figures were updates to G1. I certainly don't think the new figures look better than the old, but the CW figures have their own charm. The CW versions all needed to reformat to take on their combiner aspects. Prowl is actually a good update. Ironhide isn't bad either and frankly, I like the change to Mirage. I think the chest re-configuration looks bad. Sunstreaker is the loser of the group, but even he isn't terrible.