I actually had my first UNIX experience on HP-UX back in the mid 1980s. Would have been great to have very reliable free UNIX on very powerful and inexpensive Intel architecture as we enjoy today. Back then, you could not build a powerful UNIX machine for a few hundred bucks or a super-powerful cluster for a few thousand.
Today, there are folks who take Linux and very inexpensive Intel processors and build parallel processing virtual-machines. Governments use similar architectures to do massively parallel processing. Researchers do the same.
UNIX is UNIX, BTW. Sun OS, HPUX, BSD, Linux, AIX, etc. are all about the same - multitasking via time-slicing kernels. Learn them all. Enjoy them all. For me, I can't afford a super HP or SPARC RISC processor. I'm just a lowly engineer with bills to pay
I tend to go with 'inexpensive' and 'agile' and 'extensible' and 'scaleable'. Intel works great in my basement. But, if someone gave me a shiny new SPARC or HPUX, I would be a happy camper too!!
If any businesses want to donate a new RISC processor (rack mount only please) we will put to good use! However, please no bigger than 4 rack units, thanks. Also, please include all network card and drives. I simply don't have spare cash to pay the high price for any vendor-specific hardware.