I'm not saying that graphics and sound are everything, but I am saying that each anime has its own highlights. And in Bleach's case, the technical superiority is so strong that even major flows like a gazillion plotholes or one of the worst senses of humor to ever exist in anime just don't matter. Remember Avatar? The movie was basically crap but it did so well on the technical part that you could easily forget the plot was basically white guy meets noble culture.
For the basics: The anime's main theme is basically ghosts vs demons. Specifically samurai-like ghosts (shinigami) vs black masses with white masks on (hollows). Traitors appear on the side of the shinigamis and they side with an army of hollows so that their leader can become king of the spiritual world. Just to give an example of Bleach's plotholes... It was never actually explained WHY the traitor becoming king would be a bad thing. Granted it was a Coup De Tat but bringing peace between the shinigamis and the hollows isn't exactly a bad thing is it? The show pushes him as evil when really he never actually attacked anyone without being provoked (except for some kids in the end of the arc but really, who gives a "$%^?). Anyway that aside the show's humor is TERRIBLE, which apparently the animators realised too at some point early on and completely cat off. The story is usually dark and the mangaka isn't afraid of axing off people.
It should also be noted that half of the episodes are actually fillers. That said bleach actually follows filler arcs rather than Naruto's moronic off-and-on the main story switches. In addition, with the exception of the first filler arc (which wasn't all that bad either really) the filler arcs in bleach are actually good and they continuously get better, with the last filler arc being in fact as good as the main story if not better. In fact everything in Bleach improved as the episodes went on. Unlike some other animes (regarding pirates, "cough") Bleach matured with time, starting off as good and ending as a masterpiece.
Now for the real deal: Technically Bleach is what the Dota announcer would call "beyond godlike". The visuals gradually improved (at the start of the anime they were awful truth be told). At the final arcs practically 3/4 of each episode's frames could easily be used as wallpapers, with amazing detail aesthetics (to clarify, the resolution isn't ALL that high but the guys at the shading and art department just knew what they were doing). The soundtrack also matured as time went on. While at the start of the anime it was impressive and by far the best soundtrack that had appeared in animation at the time, in the final arcs Bleach simply had one of the best ost collections to ever appear in media in general. "Perfect" is hardly enough to describe the music, which was excellantly used by the animators.
Also important are the character designs, all of which are memorable and generally cool-looking, even for the most minor of characters. Hell, the character design of the most basic of hollows (which are basically there to die) is actually really intimidating. Character designs, moves transformations etc etc are all really well made, making it extremely hard to find a "favourite" among them.
To focus more on the music part: In most animes the animators first make the video clip and THEN decide what music to add on top of it, cutting the songs so that they fit. In Bleach the animators actually did the opposite. First it was decided which soundtrack would be used in each scene of the manga (in fact I suspect that Kubo himself WROTE the manga with specific soundtracks in mind for each scene as time went on) and then the animation was made based on it. In the final arcs you will often notice that the screen remains a second or so longer than needed on the same image. That is done so that the next clip can start at the same time the ost's next beat starts (for example see ichigo's battle with tsukishima in episode 359, it's the one where I first noticed this detail, but it was actually being done for quite some time already). As a result of this the choreography of bleach is hands down AMAZING.
Also as a result of this every battle, regardless of how small or trivial, or even of its participants, ends up being 100% memorable and pumping up. In other animes you will basically remember 2-3 scenes, the ones where the protagonist battles the big villain etc because of all the hype for the battle that the anime had busied itself creating. In bleach though most scenes will include a soundtrack that good that you will remember them without a problem (along with the soundtrack that was playing at the time). Bleach's osts range from extremely sad memorable themes (for example Torn Apart), to memorable techno-metal beats (BL 57 Sakkaku being a good example) and to memorable choirs (Treachery, Stand Up be Strong, etc etc). Pay attention to the word "memorable".
Bleach might have a loooot of problems but in the end it does so incredibly well on the technical part that they are all easily ignorable. For those that HAVEN'T watched Bleach yet, I do suggest watching just the final arc (eps 343-366) to learn what technical perfection means (no need to have seen the previous episodes, you'll soon understand what's going on easily).
