Touhou. Though I have to admit I don't play the actual bullet hell games quite as much as I used to. I've moved more towards the fighting games and random doujin titles such as:
-Touhouvania/Koumajou Densetsu (ridiculously well-done Castlevania and Touhou crossover)
-Touhou Bomberman/Detonate on Sound (best party game ever and several times more hilarious than any actual bomberman title)
-Megamari (classic megaman on steroids... except with Touhou characters)
...as well as a few others.
But I still love the bullet hell titles, "Perfect Cherry Blossom" and "Subterranean Animism" being my overall favourites in the series.
Flandre is looking forward to make your acquaintance. Assuming you can actually beat her sister on Normal, that is.
Touhou is worth it!
I'm trying to track down that one Touhou game where you play as Cirno and gain bonus points by freezing enemy bullets.
You have no idea how much I'm looking forward to Tori's pain. YOU HAVE NO IDEA HOW MUCH I'M GOING TO SAVOR TORI'S TEARS!
Now now, console gamers have their place. I mean, where else am I going to rest my feet when I'm playing my PC games?
Touhou games are generally made by just one guy, and he mixes all the music himself. The highlight of the games are, in fact, the music.
Great Fairy Wars, right? It's pretty darn awesome.
The music is part of it, but the Touhou series also have my favourite shmup games from a gameplay perspective. It especially has a good amount of really fun and intense boss battles. And while the in-game dialouges are rarely very informative, there is also quite a lot of interesting lore and backstory to a lot of the things if you just dig a bit.
Yuyuko/the final boss of Touhou 7 is probably one of my top 10 favourite final bosses of all time. Mostly because of how insanely intense and atmospheric her final spellcard/attack pattern is. And if you add the whole backstory with Saigyou Ayakashi, that part of the battle just becomes even more epic.
Similary, I also think Utsuho Reiuji is right up there among my top 10 favourite final bosses. Her boss battle fits the character so perfectly. You are fighting against a person from hell who has obtained the powers of a sun god. And during the entire battle, it actually really feels like just that. She fills the screen with giant fireballs and even small suns in a way that just prefectly displays her power.
...and then there are all the actually awesome, countless fanon things that has spawned from these games. =D