As of August 2021, in the US unless otherwise noted. If location's an issue, you CAN get around it with a VPN and that is, to my knowledge, legal.
I wasn't super thorough about searching, but in general if I didn't post it, I didn't find it. Didn't look into offerings only visible to other countries either.
Also included links for the series (or related media) on RightStuf along with their regular price, though it's worth checking back because they constantly have sales. US region DVDs/BDs, but that's obviously not a complete picture of English-language releases. For example, you CAN buy Baccano! from Anime Limited, but it's a Region B BD, so you'll need to invest in a region-free player or software that can get around that.
td;dr I'm a USAian linking USA stuff.
DEMON SLAYER:
Crunchyroll (Free/Ads)
Funimation (Free/Ads)
Netflix (Subscription)
Hulu (Subscription)
Part 1 BD (65 USD)
Part 2 BD (65 USD)
NANA:
VRV (Subscription)
HIDIVE (Subscription)
Amazon (Subscription, not available in the US)
Netflix (Subscription, not available in the US)
PARADISE KISS:
Complete manga (30 USD)
HELL GIRL:
Amazon (Subscription, not available in the US) (Season 1)
Crunchyroll (Free/Ads) (Season 4, I guess?)
VAMPIRE PRINCESS MIYU TV:
iTunes (Purchase)
OVA DVD 1 (20 USD)
OVA DVD 2 (20 USD)
NODAME CANTABILE:
Amazon (Subscription, not available in the US)
PRINCESS TUTU:
HIDIVE (Subscription)
Amazon (Purchase)
Complete BD (70 USD)
And now I'm going to plug RetroCrush because they've got a lot of older and unknown stuff (makes sense, they tend to get Discotek's releases). Completely free with ads.