HI rstermer
Square is best
pie is round but the base plate on the routers works best if it's square..
8" x 8" works out very well for most jobs,,,I'm not sure why the Mfg.make the round,most don't fit the router base right..
I could list all the advantages but the post would be to long for that
I think it comes down to ,,you can use the sq.base in more ways than the round ones, or to say one item for more than one type of job..
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