Having AC would be a plus when it comes time to sell. Check pipe insulation for asbestos in the existing system.
We’ve installed Panasonic, daikin, lg, Bryant, and Mitsu, and I wouldn’t buy anything but Mitsu for my house. To be honest none of them are great quality, but Mitsubishi has the best support and QC seems better.
They typically dehumidify better than conventional systems. If you’re not removing humidity, your system is oversized (unlikely since they modulate) or your coil temp is too high. Although the install is relatively easy, DIY systems are usually not evacuated properly and charged incorrectly. Yes they are pre-charged, but in most cases adjustments are necessary.