Look for a ground base or a thermic sandwich base if you are using a solid hob, Aga or Rayburn, especially if you leave the kettle on for long periods.
If you are using a gas hob a lightweight kettle will be fine although a heavy base kettle will last longer. Consider using a whistling kettle to prevent boiling dry.
For an induction hob you will need a base with a high iron (fe) content to complete the magnetic induction loop. Look for "suitable for induction".