My off hand response is to say "flip a coin" as I like them both and think either will make a good Senator.
On reflection, however, I think I would give an edge to Brunner because of her long standing involvement and expertise in elections law, which I believe is going to be a major battle ground going into 2012.
From her WIKI page:
During her private practice career, she focused on election law and campaign finance law where she represented a broad range of candidates, businesses, political parties and committees before the Ohio Elections Commission on quasi-criminal matters.
As Secretary of State, she has been actively involved in evaluating and adjusting statewide election systems. Her efforts have focused on correcting the procedural election difficulties that Ohio has become known for.<4> She has evaluated voting mechanisms and instituted policy changes.<2><5> She has argued policy regarding same day voting,<6> privacy of social security information,<7> and foreclosure-related voter eligibility.<8> She has advocated for greater availability and access to voting for all.