Well.....Winwood certainly was playing blues and R&B in his early days but that doesn't make Traffic all that bluesy and they did embody many jazz aspects over the years. I suppose Argent was more proggy , whateever that means , though personally I always liked Traffic a bit better. As someone else mentioned above they managed to merge several syles of music into their unique sound.

Never really thought Argent nor Traffic were all that 'proggy' ;  I like the first 4 albums by both bands.....but Traffic always appealed more to me.