Not only 6502, but first assembler I used was for Z80 at university. And PDP-11 and VAX-11 assemblers in my day job in the 80ties. Even did some HP1000 assembler.
What it comes down to: choose a tool, make it work simple examples and then use it to learn write bigger projects. The tool is not what makes a working program, it is the programmer!
After the first year assembling by hand I started using MICRO ADE on the KIM-1. Editor, assembler, debugger, non-standard syntax, tape file I/O. Lots of fun, quite big projects possible.
Then in 1985 the KIM-1 became stored and 6502 forgotten for years.
When the MicroKIM appeared I started using 6502 seriously again and since then I use two assemblers in the toolchain:
- the assembler and linker from CC65, serious software for bigger projects. Good example is pagetable's MS Basic source.
- Telemarks TASM DOS based command line. Also for Z80 for smaller one source file type programs. Integrated form Notepad++ external commands. Press a key combo and assembly done and shown in window.
Now TASM is just an assembler as many 6502 command line assemblers. Macro's supported. I am lazy so do not change what is working for me.
Subtle differences in syntax and expression evaluation may lead to hours of debugging when you assemble source form others written for other assemblers alas!
Do not underestimate this, us the assembler the source was written for!
My KIM-1 simulator supports the symbol tables from CC65 and from TASM, which helps in debugging.
The small 6502 code fragments in the KIM-1 Simulator are done with TASM.