Had to think a bit about this one...Depends on the era..
Best Magazine in the 1990's - Amiga Format. It's the magazine I bought more than any other and always checked first when deciding which mag to buy each month. CU Amiga a close second. Both mags ran good tutorials and guides.
Special mention to Commodore and Amiga review, a local Australian magazine which ran from the 80's to 1996 - it couldn't compete with AF and CU for content, but made up for it with Australian relevant Amiga content. I kept going back to the last issue until a few years ago because it had the mountlist configs needed for zip drive mounting...which I could never remember.
Best Magazine in the 2000's - Total Amiga. After Amiga Format folded, AmigaActive was interesting, but Total Amiga was by enthusiasts and for enthusiasts, and covered what we wanted to read and learn about.
Best Magazine in the 2010's - Amiga Future. The English version covering NextGen Amiga developments, exclusive interviews, game and application reviews, where are they now features and interesting tutorials too. Keep up the good work!
To be honest I didn't pay much attention to regular columns so I can't comment on those...I did enjoy the "oh dear" columns in the first few issues of Amiga Power - that was a one of a kind magazine - always biting the hand that feeds it to provide honest reviews.
Catcha,
Epsilon