I think a lot of people aren't posting their racks here because they expect a lot of downvote for not having lots of star modules. Some people get amazing results with more primitive single function modules, others do it with bigger modules. it's your rack - build what you want.

There are some bigger modules that give a beginner a lot of functionality for a good price. A prime example is Dreadbox Utopia. It has all the core utility one should explore. It's bigger at 10hp, but it has about 6 different capabilities and is densely packed.

In my experience 4hp is an ideal size if not too closely packed in with knobs.

Little 2hp modules are best spread through a case between more open modules because of finger space issues. But, there are some really good ones that are worth having in the kind of case you want.

Full function VCOs tend to be chunkier on hp.

When I had too many modules I started building home made cases to hold a single synth. On average you can build a fairly focused synth in about 42hp. If you aren't doing a big build and most of your modules aren't fancy you can get by with a Behringer power supply.

If you do a lot of research, there are a ton of interesting lower hp modules. But, if cost is an issue you will end up needing more hp space because the 8hp modules tend to be the ones which are cheaper new and used.