Don't bother getting an A/C with the highest SEER or EER. Regarding mini splits, just get an A/C with 13 SEERS and you will be set.
Inverters are listed at 20-24, which is awesome for air conditioners being used to cool your house to 65F - 70F. In CoolBot-driven systems at lower temperatures, the benefits do not carry over and there is not a noticeable difference. In a walk-in cooler environment, the actual dollars saved between the inverter and non-inverter models are so small that you won't see a payback on the inverter model for 10+ years. As discussed in the 'Will the CoolBot reduce the lifespan of my A/C?' question above, the A/C system will cycle way less in a properly insulated cooler versus a home with drafty doors and windows.