awergh,
If you tried MASM, I suppose your target is the Windows platform. In my opinion, MASM is the best assembler but it is not free for commercial use (unless you have Visual Studio Pro), but for freeware or personal use it's ok (almost all SDK and DDK include MASM).
Finding an IDE for assembly is not easy and I'm surprised that you had problems with RadAsm because I tried it once and seems to be a good one. On the other hand, assembly makes more sense to be coded in text files and use command-line to build your programs.
RC.EXE RSRC.RC
CVTRES.EXE /MACHINE:X86 RSRC.RES
ML.EXE /c /coff PROGRAM.ASM
LINK.EXE /SUBSYSTEM:WINDOWS /OUT:PROGRAM.EXE *.OBJ
or (console program)
LINK.EXE /SUBSYSTEM:CONSOLE /OUT:PROGRAM.EXE *.OBJ
or (static library)
LINK.EXE -lib /OUT:LIBRARY.LIB *.OBJ
The best start is downloading MASM32 Project and looking at the many tutorials and examples.
MASM32
Iczelion's Win32 Assembly Homepage
MASM Programming Style
Microsoft MASM Programmer's Guide
Microsoft Macro Assembler Reference
ASM Community Messageboard
If you don't already have experience with one programming language, assembly may not be the good one to start with but I guess it's not your case.
Good luck and don't give up. It takes time but it worth it.