Warthur
First of the "Sector" boxed sets which between them cover the first three phases of Rush's career, Sector 1 is perhaps the least truly essential of them owing to the fact that the band were very much finding their feet at this point in time: their debut album really isn't very Rush-like, Fly By Night is a significant improvement but has some missteps, and Caress of Steel was a bit too rushed. 2112, on the other hand, was a classic, though even then its side-long title track is significantly better than the rest of the songs on it, and All the World's a Stage is a solid live album but not a stellar one.
Nonetheless, Sector 1 does about as good a job of presenting this era of the band as is possible. The new remaster job really helps, with the pre-2112 albums especially sounding better to my ears than they did on earlier CD releases. The mini LP sleeves are an especially nice touch; boxed sets collecting five or so albums in mini cardboard sleeves mimicing the vinyl packaging are common these days, and many of them cheap out on the sleeves, but here the mini LPs feel reassuringly solid, so it's nice that wasn't treated as an afterthought. Even among those who enjoy Rush, not everyone will be too keen on all of this, but if you want a broad overview of this era of the band rather than just sticking 2112 and maybe Fly By Night, this is perhaps the best way to experience it.