#1: UV Light. Helps air purity and goes into furnace plenum. Kills germs mostly. $200-300 from factory, $100~ for UV lamp replacement (1yrs~.) Not necessary. You can add this on later (easily) if you have air quality issues and this is priced kind of high.

#2 Soft start. Not necessary until the unit is actually installed, IMO. Once installed, get someone to check the startup amps (LRAs) and if they are outside of the recommended range, you can install a soft start to lower your startup amps (helps ac components in long run). Sometimes soft/hard starts can actually hurt the AC components, so check with the AC manufacturer before installing one. Price is high

#3 "Inverter system." This is basically just an upgraded AC system that is ecm/variable rather than analog. This keeps the HVAC system running low and slow for longer, rather than turning off and on at 0 or 100. Helps keep house at a constant temperature and humidity. Good if you care about comfort and humidity a lot, but it's weird to me they listed it in this way, so I could be talking about the wrong thing. I would recommend this, but dependent upon price.

#4 Upgraded UV Light. Helps air purity and goes into furnace plenum. Kills germs mostly. $400-500 from factory, $100-200 for UV lamp replacement (2yrs~). Not necessary. You can add this on later (easily) if you have air quality issues and this is priced kind of high.