As others have said, your professor’s preference will rule. Don’t be surprised if he insists you not use a Reader’s edition. Many teachers see the definitions at the bottom of the page as one level of malevolence below an interlinear. Using the most accurate text will (and should) eventually be important to you, but early on you need something you’re comfortable reading more than anything else.
I’d recommend the (long-superseded) UBS1 (1966). It has 1) large, well-spaced text, 2) a readable font (like OCT or Loeb editions), 3) high-quality, opaque paper, and 4) a binding that allows it to lay flat while you read it *or* while you look something up. From UBS2 on down, the paper became very thin, and in UBS4 the font became thin and spidery as well.
Best wishes!