We know vamps are stronger than humans, at least on average.... though I don't think all of them are peak human based on performance against Scoobies....but maybe peak for their body size and musculature....And older more elite vampires in the Cap to 1 ton range
We also know Buffy could easily lift the troll hammer one handed and Spike couldn't lift it without maximum effort. She could bend the bars on jail cells as well. Her strength wasn't played up a lot, likely do to budget constraints, but I'd put her in the Beast ballpark.
She is weaker than Dracula, correct?