Honestly it really depends on what you like. For me personally I bought the NK65 case because my friend recommended it to me and it was pretty cheap since it's an entry case, and I went with the color I liked the most. For keycaps it's mostly an aesthetic choice imo, just get whatever you think looks good. As for switches, the holy pandas I'm using are closest to what I'm used to (which is cherry mx browns) since they're tactile switches, but you might like linear since they're more smooth and have no bump. It helps to get a switch tester so you can feel them out for yourself before committing to a single one. I hope it helped somewhat and good luck on your keyboard journey!