Man, as someone who’s obsessed with vampire lore and action-packed anime, I could talk about 'Hellsing' and 'Hellsing Ultimate' (I assume 'Integral' refers to the OVA series) for hours. The original 2001 TV series 'Hellsing' was a fun ride, but it deviated from the manga pretty early on, creating its own storyline. It had a darker, more gothic vibe, but the pacing was uneven, and the animation quality dipped at times. On the other hand, 'Hellsing Ultimate' is the definitive adaptation—faithful to Kouta Hirano’s manga, with brutal, over-the-top violence and way more Alucard carnage. The OVAs had a bigger budget, so the fights were smoother, bloodier, and just… more satisfying. Plus, Integra and Seras got way more development.
If you’re new to the franchise, I’d say skip the 2001 version and go straight to 'Ultimate.' It’s like comparing a fast-food burger to a gourmet steak—both have their charm, but one’s clearly the full experience. The original’s soundtrack slaps, though; 'Logos Naki World' still gives me chills.