What HP calculator should I buy

[setq]

Hello all,

Potential new HP calculator user here. I mainly use a Casio FX991-ES PLUS for electrical engineering work. It does most of what I need but I really want something with rudimentary programming ability to automate a few tasks which I do regularly. Nothing complicated. The Casio programmables don't cut it really. However after playing with a friend's HP 41 and 48, I'm slightly hooked on RPN/RPL machines. It works how my brain does.

I don't use the Casio for a whole lot, mainly unit conversion, basic calculations (engineering units, trig, polar vecotrs, no calculus) and the solver.

So the question is, ignoring the vintage calculators as I want a new one, which one is likely to benefit me the most: the HP 50G, the HP35s or the Prime?

I'm edging towards the 35s at the moment as 50g's RPL programming is significantly more complicated. That is manageable but I'd rather have something that fits in my head looking at the programming manual for it!

Anything I need to know?