Had a really psychedelic dream about Axew last night and woke up unable to think of anything else so yeah I'mma ramble about it for a bit, why not
The Axew line have long been my favourite Dragons for many reasons. This is partly on the basis of aesthetics - its real-life basis is incredibly interesting, it has a superb shiny, and each stage of the line is well-designed and has its own distinct appeal - as much as it's due to the marketing it received; it was very cool to have a Dragon-type be a prominent member of the main cast in the anime during Gen V. It's one of the better-designed mons of Gen V imo, and my favourite line from that gen.
It has by far the most notable cute-to-serious-to-deadly progression of all the dragons up to that point (Dragonite isn't threatening, Larvitar is cute but already has an attitude, Bagon and Gible are pretty serious in their own right, and Deino just isn't cute). Gameplay-wise, it's so much fun to use because it gets everything it needs to perform well. It has the sort of expansive movepool a Dragon should have (it even gets an OHKO move); even in games without extensive move tutors, it learns enough to cover everything it needs to.
Without descending into competitive discussion, I also like that Haxorus's stat spread is so efficient. It's got an Attack stat that eclipses all of the pseudo-legends - you'd expect such an overspecialised Pokemon to be hobbled to compensate (see: Rampardos, Shuckle, Deoxys, Blissey). But it's not. It has a Speed stat that's... actually really decent, passable HP and Special Defence, and surprisingly has good enough Defence to take some physical punishment and occasionally avoid being felled by strong neutral moves. The fact that it has such great stats with minimal drawback is largely by virtue of it sitting in that lovely "not quite a pseudo, but better than the vast majority of mons" tier also occupied by Arcanine, Kingdra, Florges, Flygon, Lucario, Rhyperior and a select few others which is a nice place to be.
It's designed to hit things and be quick, and it does that very well. Few Pokemon have such efficient stat spreads; often I look at a Pokemon and think that if it only had 10 or 20 points more in a certain stat it'd be so much better, especially if the numbers in question were deducted from its lower offenses to keep its BST the same. Druddigon for instance is an example where even 10 points deducted from its Special Attack and reinvested into its HP would make it a lot better - it still wouldn't be great, but certainly better. (Disclaimer before anyone jumps down my throat: I'm not saying that I want more Pokemon to be minmaxed, I think most are ultimately fine as they are.)
But yeah. Haxorus succeeds on numerous metrics. Top-quality design, top-quality shiny, top-quality battling ability, and to paraphrase Junichi Masuda (iirc) it's one of those Pokemon which still looks like it can be your friend even though it's ferocious. Here's to the best Dragon line! Though I do love Dragapult too...