tiagra will be your best bet.
You can't buy 9sp ultegra new anymore, and the ergonomics of the lever itself is questionable.
The current generation 9sp tiagra STI levers are way better ergonomically and functionally than the previous generation 9sp 105, ultegra and tiagra levers.
current gen. Sora STI levers are better built than the previous 8sp levers, but still leave a lot to be desired over tiagra, due to a variety of reasons.
Another alternative is to use 10sp 2009 campangolo veloce levers and a J-tek shiftmate or "B-routing", because I know someone will mention it. Quite frankly, the Veloce 2009 levers are better than Tiagra and the prices aren't that different, but it's slightly more hassle to mate them to a shimano 9sp drive train.