Seeing that the Motion and Groups programs are being obsoleted, I converted some of my RM that were using Motion or Groups to use the Room Lighting program. So I am now wondering what are the reasons for using Room Lighting Vs. Simple Rules Vs. RM when any of these programs will suffice for a given situation. It seems like Room Lighting and Simple Rules might appeal more to people that prefer a more visual interface while RM might appeal more to people that prefer a more boolean logic kind of interface, I am also assuming that using Room Lighting and Simple rules are slightly more efficient than using RM.
Is there any guidance for when and why to use one of these programs Vs. the others?
Not to add to the complexity but there is also Basic Rules......
I currently use a mix of Basic Rules, Room Lighting, and Rule Machine. If it is a simple automation I would probably use Basic Rules. I have started using Room Lighting for my motion sensor-control applications, although you could use Basic Rules for a simple application.. Then I use Rule Machine for more complex applications.
Like it says in the above link.....choice is good.
Room Lighting is geared specifically towards lighting and is capable of replacing (and, in fact, can import existing instances of) Motion Lighting, Groups, and Scenes.
You can use Rule Machine for pretty much any of this too; the idea is that a Room Lighting instance is generally easier to set up, as you don't have to think through the logic--Room Lighting does that for you. This is similar to why you might prefer other purpose-built apps, like Notifications, even though Rule Machine could handle it, too.
Simple Automation Rules was originally basically an even simpler Motion Lighting, though the capabilities of the app (which was once called Simple Lighting) expanded over time. Basic Rule, as mentioned above, is an even newer app, and you can read the thoughts behind its creation in the post above (in short, they believe they've learned some things over the years, and it probably flows better in terms of how most people think of creating automations).
On a related note, I'd probably recommend Basic Rules over SAR to new users at this point, though both remain. Sometimes they do simplify things, like they are trying to do now with offering only Room Lighting to new users instead of Motion Lighting and Groups and Scenes (I'm almost surprised not to see SAR on this list ). In all cases, setups existing users have made will continue to work. For complicated lighting automations, Room Lighting is probably the best choice now, though Basic Rule (or SAR or any app) is certainly fine too if it meets your needs.
In the end, I think, there are no hard and fast right or wrong answers. I think the responses so far encapsulate the general approach that is recommended, barring any corrections from Hubitat staff, but there is also the human element and what makes the most sense or fits within your own experience and knowledge. I think it would be worth trying each of the options available to see what suits your needs best, but still keeping in mind the intended use cases HE is targeting with each, making sure you aren't trying to stretch the app in directions not intended by the developers.
And to also treat it as a period of discovery, where you work out what types of automation you want to do where, being open to changing tack if needed.
The apps are like shoes. Use the one that fits best for the occasion. Basic Rules app is like running shoes. Comfortable for most use cases, but if you want something more fancy, then go with Rule Machine. Room Lighting is geared towards parties. Easier to use when multiple devices are involved.
Efficiency is not a problem. It's a matter of preference. For example, I prefer to create multiple instances of Basic Rules, but others may choose to have just one rule that handles different actions. Sometimes you just can't use Basic Rules because the trigger may be too complex for what Basic Rules can handle.