I have a Falistri and a Maths and like them both. Falistri does a ton for 18HP and it does have some really unique features. One thing I will point out that I don't like about it though is that the green and yellow sections are not actually function generators, they're envelope generators which means that some of the cooler things Maths can do Falistri can't. So from my PoV if you're interested in learning some of the basics of analog synthesis, if you value tactile interaction (IMHO Maths is the more ergonomic of the two) and you have other support utilities Maths would be the pick, if you don't have much room for other utilities and you just need a module to get 5/6 different things done pretty well, then Falistri is a solid choice with the bonus that it can also function pretty well as an oscillator.
my tunes: https://stevehand.bandcamp.com/