In your situation I recommend Residential 100 Mbps. It's more than enough for what you described. By picking the 100 Mbps plan, you are saving $75/month ($130 vs $55 per month). That pays for an outright Mini purchase within 4 months. Also, the Mini rental requires a $10/month Standby Mode fee. A purchased Mini is allowed to completely cancel service, and not use Standby Mode if you choose not to. That's additional savings to consider.
Alternatively, you could keep the Mini rental assuming you keep paying the $10/month Standby Mode fee, and still downgrade your plan. Starlink allows this as long as you keep paying for the Mini Standby Mode fee.