I have used the TI calculators for many years and have gotten used to the algebraic entry and the keyboard layout. Now I use the TI-30XA which is a solar powered and costs about $12 to $14 US. Actually I have 4 or 5 of these spread around in places like the home, office, briefcase, job-site, etc. It's a decent calculator with a good feel to the keys. To me it is important that a calculator have the square, square root, inverse and pi as primary functions and not require hitting two keys to get to these functions because of the frequency which they are used.
My son has a HP-88 and 89 and these are nice machines. The 88 is much better than the newer 89 according to him, but they aren't cheap and don't fit into a pocket easily. I realize that RPN is a better system but it's not for me. I've been programing in BASIC for twenty years so have never really been interested in programmable calculators. During the last few years I have moved to Mathematica CalcCenter for almost all my calculations except for simple adding, subtracting, multiplying, and dividing, which I use my TI-30s for.
It makes sense to me, but I'm sure there are many opinions on this subject.
Regards,
-Mike