Best automatic litterbox?

Any recommendations on an automatic cleaning litter box?

• 2 cats
• Don't really care about smart features, but prefer NOT to be required to use Wifi/Smartphone.
• Not interested in changing litter or using proprietary litter formula
• Not interested in models that require replacing consumables (filters, sprays, mats, etc)
• Covered preferred but not required.
• Under $500 Thanks!