You definitely don't have Rule 1.0 on Hubitat (it pre-dates Hubitat) but possibly Basic Rule 1.0, which is a newer app and a different app, part of Basic Rules and not Rule Machine. The latest version under Rule Machine is Rule 5.1, but you are still likely to see a lot of posts about Rule 4.0 and others. All this to say there are many "rule" options on Hubitat, including:
- Rule Machine: the most powerful option, but it is a large and complex app that can be difficult to learn if you're new
- Basic Rule: a simple "when this happens, do this" builder; despite the name, it can still do quite a lot but has a simpler interface that is probably more in line with how people think about creating automations
- Simple Automation Rules: formerly called Simple Lighting and originated with that purpose in mind, but it was expanded to support more device types and "actions"; I probably wouldn't recommend starting with it at this point given the other options
Soon, there will also be another built-in option:
- webCoRE: a community-maintained app (which I assume will still be the direction even after integration) that originated on SmartThings but was ported to Hubitat early on, featuring a web-based "piston" (rule) editor
There's more history on webCoRE (and RM) too, but that's a basic summary. 
If you're comfortable with IF THEN logic, Rule Machine or webCoRE will be your best bets (notably, this kind of logic is not possible in Basic Rule, at least not on a granular level using this exact terminology). There are certainly some things that are easier to do or edit in webCoRE, but Rule Machine is a lot more powerful and has an improved interface now compared to earlier versions, so many people who originally avoided it in favor of other options find that it can now do what they want instead.
RM is likely a tad more efficient being all "native" Groovy on Hubitat, though a small purpose-built app will likely be a bit better than either. It's likely to get better "official" support being built-in and supported by a dev who is also a founder, but I'm not sure what the plans for webCoRE are (my guess is ongoing community support from the current maintainers, who have done a great job, along with staff, at optimizing things--so I'm certainly not implying there is no support!).
My personal approach is to use the simplest app that meets my needs; hence, I have my automations spread out among many built-in options, like Notifications, Basic Rule, Mode Manager, Rule Machine, and others -- plus a variety of custom apps I've written for various purposes. Maybe webCoRE will become part of that again; I've always kept it around on a test hub since it has some following, but I haven't done much with it in years in favor of the other options. As usual with Hubitat, there are multiple ways to do the same thing, and some of it just depends on your preferences. 