"Who's the better strategist? Who achieved more? Who made plans that actually made sense and worked out? Who's the better "deceiver"? Who caused more fear from their foes? Sauron or Morgoth? Who's more intimidating? Who had the better "end"?"
Better strategist... I think Morgoth, looking at the wars of the First Age. He simply dared more... like, destroying the Trees, stealing the Silmarilli and so on. The coolest thing Sauron did was the Drowning of Atalante... and he laughed π
I'm not really sure who achieved more... Sauron held Middle-earth under his dominion longer, but Morgoth wiped out nearly all Beleriand π (Gondolin was the only free city for a long time... until it was destroyed, too........)
I dont think any of them made real plans or something, they used the advantages of each moment π hm perhaps Sauron planned the Rings and the Drowning of Atalante while Morgoth had a long time to plan the Dagor Bragollach π and the Dagor Dagrath maybe when he killed Arien...
I think that Sauron caused more fear than Morgoth, though I dunno why... maybe it's only because Tolkien doesnt describe people's feeling as much in the Silmarillion (as he does in LOTR). Morgoth was also somehow a little more "real" than Sauron... I mean, he even answered to Fingolfin's Challenge, and many of the Eldar saw his real body (not only in NΓΊmenor, Eregion and the Last Alliance as it probably was the case with Sauron), as Finrod also describes.
The greatest thing Morgoth did was to spoil Death, I think. Death isnt anything one should be afraid of, but Melkor made it seem evil especially to Men (great passage in the Athrabeth!).
The better End was also definitely Morgoth's... if you can speak of an end in his case π his end was the real End Of All Things...