Best scientific (not programmable, not producing plots) calculator in your opinion.

[bhtooefr]

Here's the entire list of HP RPN scientific non-programmable calculators, as far as I'm aware, in chronological order:

HP-35 (1972)
HP-45 (1973)
HP-21 (1975)
HP-27 (1976, also had statistical and financial functions)
HP-31E (1978)
HP-32E (1978, also had statistical functions)

Everything else was programmable.

Do note that in some contexts, programmability - even if it's not used - is unacceptable. For instance, a friend of mine has a TI-36X Pro that she carries specifically for classes that forbid programmability on calculators used in tests.