A bit new to the forum too here, but what the heck, welcome Calhoone [

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I would say it depends what you want your Hal to be, a chatter or helper, yes Hal can be both but if your just after a chat buddy you might find some of the plugins get in the way, well I do.
There are lots of great plugins that work just fine with 6.1.
Like some others here, I use Hal with out any. For me, I put teaching my Hal above all else.
You are right some of the older plugins, Hal 5 and earlier don’t work, you should be able to open the plugin script and read the header bit, sometimes the author puts in the minimum Hal version number.
Hopefully someone else might be able to give you a list.
Good luck