We've stayed at the Courtyard by Marriott Theme Park. It's a nice hotel, clean and spacious. We just weren't wowed by it and haven't stayed since. The bunkbeds are nice, but there was nothing special about the hotel to make us return. Maybe it felt too sterile? lol
Harbor is safe. I've walked back to the hotel to grab coats or random stuff we forgot at night as a single 19-24 year old female and had no problems. My mom is always paranoid about this and will have either my brother go with me or watch from the hotel balcony if I run to pick up Denny's or stop by the convenience store for water. The area is really not that unsafe. My field is criminal justice and I enjoy researching crime rates in the areas we travel (weird, I know). The crime map of Anaheim along Harbor shows that the most common crime to occur since October is shoplifting, larceny, and a *rare* assault/robbery. Knowing the area, I am thinking the crimes against people are within the transient population and are not acts committed towards tourists.
The transient population is not huge by any means. You may see at most 5 people (in recent times, there used to be more before COVID) hanging around the area, but it's not something that you won't be able to avoid. They won't interact any considerable length with you if you just keep walking. There are also vendors who are just outside of
Disneyland property, but they are harmless. They sell water, toy helicopters, balloon-type light up things, etc. Though we've had no issues, we always just stay right across the street and plan on heading back to the hotel during hours where lots of people are heading back (think 12:30am at the latest for a midnight park closing). There are always people walking back before and just after park closing, so you're never completely alone.
Security has been moving very quickly recently. Before COVID-19, it wasn't unheard of for us to wait 30+ minutes in security and it be backed up with wall-to-wall people near the buses. Now, we wait maybe 5 or 8 minutes at most because they are very organized and have many lines constantly moving.
With that being said, if it was a choice between Courtyard and Westin, I would choose Westin. We haven't had the opportunity to stay there but it looks really beautiful and nice. I don't have any experience with the opposite side of Disneyland (where you would be walking to get to Westin), but I haven't heard of any major incidents happening on that side. Disneyland Dr. appears to have the same crime types as Harbor according to the crime map, so I would say that area is probably safe as well.
EDITED TO ADD: I actually just took a look at the map again and it turns out there are more assaults between Katella and Ball on Disneyland Drive than there are in the same boundaries on Harbor. I'm not sure why so many assaults would be occurring on Disneyland property (parking or DtD maybe?). Just wanted to add this.
