Hellsing Ultimate, Black Lagoon: Roberta's Blood Trail Recommendations
Similar looking, eyes, hair etc. BL:RBT is a lot more cruel than first and second season, it's more like Hellsing, dunno why Revy reminds me of Alucard.
both are epic, bloody and revy looks like alucard in many ways
Both involve heavy gun action and splatter. Black Lagoon has not as much splatter, though. Make sure to watch Black Lagoon TV before but its not as violent.
Action packed fights with cruel, sadistic, and cringe worthy scenes from both OVAs.