Lava is a less expensive option, therefore easier to replace if needed, however Lava emit less heat than glass.
Warning! Lava also can absorb moisture and might pop when the fire is lit and it gets hot. If it was raining even if fire bowl was covered Lava still might have moisture in it. Let Lava dry as much as possible and let fire bowl work for 10-15 minutes while standing away from it. As sometimes Lava will explode and could be dangerous.
If you have kids around the fire bowl when the fire is off lava might be less "appetizing" for kids than glass, especially the glass beans that might look as a candy.
Always watch children around the fire bowl.