I generally agree with @Lugia's advice to avoid in-rack percussion, especially in smaller racks, and followed it myself for a long time. However, I got a good deal on EC + SS while filling my fourth 104hp row, and after working with that and external drum machines for a while (using a CV-to-MIDI module), I bought QD. This still may not be the right decision for you, but here are a few points in their favour. EC is very playable. Euclidean capability is relatively rare in standalone drum machines or sequencers, and even when it is present, it's unlikely to have a good UI. Pam's gives you the capability in-rack but I didn't consider it playable (it's fine for set-and-forget).
Unsurprisingly, QD works very well with EC, and is also quite playable on its own. With both EC and QD, you can do most of what you need in a straightforward manner, but for some functions, you will need to consult the manual to understand what the lights mean (often these are just configuration settings). QD can play your own samples (it comes with a good library) and it has the mini-Rings part of Plaits and, I suspect, the percussion models (or something very much like them). You also have Plaits and One in your proposed rack, but I would encourage you to instead consider for that space some of the more complex and unusual oscillators available, such as the new Bastl Pizza. QD also has a compressor and (as an Easter egg) a delay and reverb. You could eliminate the tiny 2-3hp effects modules, which are going to be a nuisance to work with. (If you don't think QD's effects plus Beads is sufficient, consider the 6hp FX Aid XL.)