As much as it pains me to say it, the Steelers have a clear edge with Roethlisberger. Dalton was better in week 1 of the 2013 season, but Roethlisberger is 13-5 all-time against the Bengals (1-0 in the playoffs), 63% completion, 22 TDs, 18 INTs and countless deflating defeats. He also seems to have the ability to play better the bigger the game (see 2 Super Bowls for proof). Dalton on the other hand is 1-3 all-time against the Steelers (and has never scored more than 17 against the Steelers defense), 52% completion, 4 TDs, 5 INTs, and 172 y/g average. Dalton, unlike Roethlisberger, seems to shrink in big games (0-2 in the playoffs with 0 TDs).
The Steelers gave up 36 sacks last year and their leading rusher (Dwyer) had only 623 yards. If that wasn’t bad enough, they lost their starting LT from the last 6 years (Max Starks) and replaced him with 2nd year disappointment Mike Adams; they lost their starting G/RT from the last 6 years (Willie Colon) and replaced him with Ramon Foster, and now they lost their Pro Bowl center (Maurkice Pouncey) and will try and replace him with their 3rd string center Fernando Velasco.
In 2012, the Bengals OL was not great, giving up 46 sacks, but many of those were on Dalton. The Bengals did have a 1,000 back in BJGE and with the exception of Whitworth (out with injury), return the same bunch. While Anthony Collins may not be the player or leader that Whitworth is, he is a highly capable backup (faced Peppers in week 1 and allowed 0 sacks).