I think that the S&W Sigma is a well made pistol (current production). The Ergonomics are great, good sights, well built design, etc.... Only issue is the trigger pull. You a good smith can smooth it out but sadly Smith & Wesson does not do that themselves. They go bang every time and are S&W's number one selling pistol. If you cannot afford anything else or get a great pistol for a steal. The Sigma will serve you well....
If you can though, get a S&W M&P. It's the cat's ass. Other than that I say GLOCK or Beretta.
The S&W M&P series took everything that made the Sigma so great in terms of ergonomics. Gave it a lighter trigger, removable palm swells, great sights, and a GLOCK type action with a little Sig Sauer and Ruger thrown in.
Before I owned the M&P I was a die hard GLOCK and Beretta 92FS fan. But Smith & Wesson really improved their image with the M&P series.