An investment in any of the sanders you mention is a waste for a single house.
The high quality tools are always preferable because they are built do to actual work, and with a powerful motor and strong bearings they are meant to last for years for a professional user. But they cost a lot. A professional will see his investment back because he will use it on dosens of houses each year, for a couple of years. A home owner will not.
A cordless Makita? You will need to stop and change and charge batteries all the time. I could never live with that. There are so many better corded options available. Doesn't need to be the most expensive there is, like the Planex, other manufacturers also make them. Flex, Milwaukee, and apparently the Porter Cable 7800 is great value for the money.
- Stay away from the WEN. It's a sham. A penny spend on that WEN is a penny thrown in the bin. That particular sander is available all over the world from dosens of cheap no-name brands. It is just a cheap generic Chinese product that is only made to look like a drywall sander but isn't really functional. I know somebody who had one. For instance, the round head DOES NOT SPIN like a drywall sander is supposed to. It just vibrates like an orbital sander. And at a very low RPM for that. Also, it overheats after 15 minutes of use. And last but not least, it uses a proprietary type of paper that is nowhere to be found. The guy I know who had it threw it away after using it 2 times.
But want to work on your house and get a sander that works and doesn't cost a ton? Get an ETS 150, EC or not, and you can use that sander for your drywall and tons of other jobs.