Here is an idea I had that can be fun to do if you like a lot of decks but many of them aren't viable in ranked. Take a group of decks according to some theme, a number divisible by 2, so something like 8, 16, 32, or even 64 would work well. Try to not have any deck with overly high power compared to the rest of them, so the result is unpredictable. Then make a tournament bracket (good site I found to do it easily is https://challonge.com/tournament/bracket_generator but can just do it on paper too).

Finally, you can do it with ingame hs friends where for each deck matchup you would do a friend challenge (they can borrow your decks if only one person has them) and play 3 games. You can switch the person playing each deck once too. The deck that wins best out of 3 (or you can set it up to be best out of 1, out of 5, whatever you prefer) moves on to the next round.

You can keep doing this until you get the final winner. For me this type of thing is very enjoyable (the suspense of which deck will move on to the next round and being able to play a huge variety of decks against others of a similar power level and not worry so much about the meta) but I only had the idea to do it yesterday, so I wanted to share the general idea in case anyone wants to try.

Here is an example bracket for the first tournament I'm doing (theme is off meta ones, specifically ones on the weaker side of things and/or very rarely seen).

After that I'm planning to do a tournament of 32 reno decks from all different classes for some kind of ultimate reno deck showdown.

Overall, lots of options and you can set it up however you want. Maybe do a tournament of decks from just one class or using only cards from certain expansions, many possibilities.