For smaller code and faster speed, assembly language is the best. But if you want the project to be designed in a couple of days, use any of the high level languages. I prefer C because of its advantages over basic like pointers and other things which are quite helpful when you have limited RAM.
XCSB is a structured PIC BASIC. It generates machine code which is directly executable on the 16F84. It allows you to create user functions and understands pointers (like C). It is in ALPHA at the moment so its usefulness to you will be limited, however it does generate decent code for 8, 16 and 32 bit integer and floating point operations (together with an assembler listing) so it should help you convert complex expressions into machine code. XCSB is at http://www.xcprod.com/titan/XCSB
If you don't want to go that route you could also look at http://www.xcprod.com/titan/web_demo.html here you will find an online demo of the XCSAM assembler. You can type high level expressions into the web page and they get converted to optimised executable assembler for you.
you can find manul and compiler in Basic it's very easy to use just one or two month
it compile all pic like 12c 16f 18f dsp30f and etc
http://www.mikroe.com/
like this: View attachment compilers_ide.pdf