Link directly to rack for reference : )
It's extremely common for newcomers (myself a year ago) to want to start small and think it'll hold you off before you expand, but cases are a real expense. If you know you're going to expand, you might as well start with a case that will allow you to grow into it. I started with a Tip Top Happy Ending kit (3u, 84hp), got a second set of rails and mounted them in a box (6u, 84hp), but by month 4 or so I had already filled that and knew there was more functionality I needed. I recently got a 9u 104hp case from Case From Lake that closes patched and would recommend them in a heartbeat. It's just one guy out of Italy so took a little while for it to get finished, but well worth the wait. Otherwise, the Tip Top Mantis is the best bang for buck case, has a great power supply, and really is quite portable. Those Palette cases look cool, but are substantially more $/hp for what they are.
Looking at your assortment of modules, I think you will run into some additional needs quite quickly in terms of utilities, which in the Palette case you won't have room for. EG Monsoon reeeaaaalllly needs attenuation on modulation, and right now you only have the 2 vcas in the 1u row that can scale back in that way. Sloths is going to swing those parameters pretty wildly, particularly if you use those bottom +/- outputs which can go outside the +/-10v range. Sloths is also chaotic by nature, and I think you'll find that having something that can do "normal" LFOs is extremely useful.
Those are the things I've noticed for now. The modular journey is incredibly satisfying, but once it gets its claws in you you're going to move up in hp quite quickly : )