Square-1. I love square-1 and it's my favorite event by a mile. If you enjoy 2x2 square-1 will be a good event for you. If you think about it Square-1 is a better version of 2x2. Both events are almost completely alg based but Square-1 has a ton of small optimizations and such. There is not a lot of people that seriously do Square-1 as of right now so its very easy to rise up the ranks (Only took me a year between learning how to solve it for the first time and breaking into the top 1000 from September 2018 to September 2019). Unfortunately, I have not been able to compete since October but that is another problem with Square-1, it's not held very often. Luckily where I live its held very often due to a high volume of competitive solvers but in some places, it's only held once or twice a year. anyway, the Square-1 is an interesting puzzle that rewards high TPS along with slight alterations to regular algorithms that can give you an advantage. I went into squan with the mentality that its an awful event but I have come out the other side with nothing but good things to say for the event (aside from hardware, the volt v2 is pretty good but we still have a long way to go). If you want a challenge with something new, I would put square-1 at the top of the list.