If you're new and just want someone to suggest something to you, then I'll suggest starting with Basic Rule and ignoring Simple Automation Rules. Basic Rule is newer, arguably has a bit cleaner/simpler UI, and can do many of the same things (Simple Automation Rules was originally called Simple Lighting and you can read about its origins above, but it's grown in scope since).
Some things will be too complicated for either and will need Rule Machine or a custom app--or one of the many purpose-built built-in apps available. For example, the Notifications app can handle many common cases for notifications that you might otherwise think you'll need a rule-type app to do (e.g., send a notification if this sensor reports this temperature between these times)--though, of course, you'll ultimately get more flexibility, should you need it, with the former. I think some people ignore these in favor of some sort of Rule for everything, but I prefer the simplicity (or complexity) of a built-in app when it suits the automation, and they're generally much easier to set up.
But like anything, your preferences may vary. Doesn't hurt to try something out and then try something else if you don't like it! Just like lots of arbitrarily powerful systems, there are multiple ways to do pretty much anything--but unlike many of them, there are lots of purpose-built things included already to get you started with common tasks without needing to think about "rules" at all (e.g., Mode Manager, Thermostat Scheduler, the aforementioned Notifications app, and many others). I much prefer this approach to systems that make me do rule-type things for everything myself, which I have used/tried in the past.
Whatever differences there are in resources are immaterial.
We can't remove SAR just because Basic Rules came along, there are lots of existing SAR automations out there. Nor, just because SAR existed would we stop trying to make improvements to the platform, and improve the apps available, nor volunteer to munge things together for the sake of having only one. For goodness sake, no one is asking you to learn two different apps. I wrote both of them, so blame me, but your complaint rings hollow.
FWIW, I have moved all of my automations that I had in SAR to Basic Rules, as I prefer its UI and flow, and the logging is better. Basic Rule represents years of learning and experience about how to create automation rules. SAR was a knock off of an old ST app. If you only want one, go for Basic Rules for sure. I would only use Rule Machine for something I could not easily do in a Basic Rule.
The last paragraph is exactly the info I was seeking, and probably a number of other users.
If you don't understand why users would see three automation methods, and seek one of:
Be guided as to which one is, most often, the better choice (and "why", if possible)
Need to try each out to figure it out for themselves, using far more time than (1) above
...then that's often the problem of the product manager not understanding a segment of the users. Everything is familiar to you, nothing is obvious to many of us. But you're building the UX for the users, not the developers.
That said, in the final paragraph you wrote, and from a few other users here, there is absolute consensus that Basic Rules is probably the right place for newb & semi-literate users to start, and to continue there until they seek more power in Rule Machine. That info should be in your help sections (some of which I had read), and probably also in the UI itself at the top of each Apps first "Create new" page. It could be there as a one sentence reminder, with a link out to the help page.
Not sure if you're aware of it, but we pre-install Basic Rules on new hubs -- it's already there before you do anything, on the Apps list. You're right though, there should be more verbiage to explain that, and point people to it.
Rule Machine would suffice as a one stop shop for all. It can be used to create basic automations, or very complex ones. It is also the most resource intensive of the group.
On smaller networks, it's not a big deal, but on larger networks with hundreds of devices and hundreds of automations, a noticeable delay can be observed.
While everyone is entitled to their opinion, having multiple options is always a great thing as it doesn't lock individuals into one way of doing things. Competition breeds evolution, even if it's within the same platform.
At the end of the day, as long as you can complete your automations successfully and in a timely manner, it shouldn't matter how a person does it.
Basic Rule is newer, arguably has a bit cleaner/simpler UI, and can do many of the same things (Simple Automation Rules was originally called Simple Lighting and you can read about its origins above, but it's grown in scope since).
