Alow me, to once and for all, answer this most burning of questions, 'I'm new to Gunpla, what should I build?"
Have you ever built a model kit before?
Pick a High Grade or RE/100 grade kit.
Doesn't matter what kit you get, go with whatever design you like the best.
Any damn kit you like
Seriously, you got this
Seriously. Stop. Don't overthink this.
If you haven't built a kit before you can't go wrong with the simplicity of a High Grade or RE/100 kit. The complexity is low, the part count is low. The process isn't fundamentally different than any other kit, even Perfect Grades.
Yeah, some HG kits are better than others. It is a product line that has been around for over two decades now (in its current form). But this isn't about building the best kit, this is about you. You building a design you like. You, getting to know the build process. If you mess up, break something, that's okay. I'd say a majority of us in this hobby look back at our first few kits and cringe a bit.
Oh, you've built model kits before?
Sweet, get whatever you want! You can 100% jump in and get the PG RX-78-2 unleashed. Gunpla kits are just like all of the model kits that have been around for decades now. Well, they're 100x better since Bandai's QC, molds, and documentation are the leader in the space.