If you want something with a bit of sporting intent in the way it rides, the Triumph Speed 400 makes for a good purchase. It is a relaxed city commuter with good suspension, a smooth and grunty engine, as well as an agile demeanour. If you want a more mellow riding experience but want a Triumph, the Speed T4 makes a good case for itself.
If you want bikes with a more old-school riding experience, then the Honda CB350 models and the Royal Enfield Bullet / Classic / Hunter 350 models deserve your attention.
All bikes here have been out for multiple years now and have largely proven themselves to be reliable machines.
A test ride of these bikes will help you decide which one suits you the best.