For 99% of users you do not need the much more expensive pure sine wave inverters. Your computer laptop has a brick power supply which takes that AC and converts it to pure DC before sending it to the laptop. I use the cheapest possible modified sine wave to charge and run mine and have for years and years.

The biggest users of pure sine wave are some medical devices and some (older) communications devices (not the DC kind) which are RFI sensitive. Most modern equipment is better designed to handle RFI and EMI and don't require the expense of pure sine wave.

In the house I have a home made 9000 KW USP running into a modified sine wave inverter which runs my freezer, ham radio, and lighting. I'm a communications volunteer in the local community (RACES) so the "ham shack" needs to be on-the-air during power outages.