What do I want to achieve?
Hi there! I made in the couple months a lot of GUI’s, but I want now to make more advanced onces. Because I know how you make good GUI’s in roblox self, but if I want to make more advanced ones, what programs should I use?
Thanks for reading and tell me what you would reccomend me to use 
Personally, I use Affinity Designer because it is easy-to-use (or at least for me), smooth, and gets the job done. Another big plus is that it works on my MacBook Pro and my iPad.
UI Design Tools are helpful visualisers but generally unhelpful for helping you understand scaling and UX - by the same stroke of the pen, it’s why (real) web developers rarely design their pages in HTML editors.
There are helpful things you can learn though - like 9-Slicing, and also constraints, that’ll help your UI perform well 