Now, I have seen the Season 1 episode Nightmares and the Season 5 episode Buffy vs Dracula more than once, and I have more than plenty of good things to say about both episodes as well.

Basically, I can see what could've happened if Buffy had chosen to become a vampire in Buffy vs Dracula. From my perspective, it is possible she'd look almost similar to how Dracula looked with the human face and perpetual fangs — unlike the demonic Hellmouth vampires and how they looked with the ridged forehead and yellow eyes whenever they were about to feed on their victims, or were placed in stressful situations, such as fighting.

Also, ironically, all it took for Buffy to get over her fear of becoming a vampire was having that fear manifest (although it had been temporarily) when Billy Palmer's astral form brought the nightmare world with him to Sunnydale. 

Thankfully, as a Slaypire (which meant both Slayer and vampire), Buffy was able to get the upper hand in her battle with the manifestation known as the "Ugly Man" (as Billy called the manifestation of his fears and his inability to deal with being put into a coma by his Kiddy League Coach, who blamed him for his team having lost a baseball game) and take him down — whereas before, she'd been easily overpowered by the manifestation despite her being the Slayer. 

(And speaking of which, as one of my friends once explained to me, Buffy was quite loveable even as a vampire, as well as downright sisterly to Billy, given how she acted towards him in the episode. And I couldn't agree more there, too.)

Plus, I recall this part from Nightmares the best:

Kiddy League Coach: (comes in as Giles and Xander are about to go get a doctor) Oh! Huh. Billy's got company. (He takes off his cap) I-I-I'm his kiddy league coach. I come by here every day, just hoping against hope that he's gonna wake up soon. He's, uh, my lucky nineteen. (Giles and Buffy exchange a look, and Buffy realizes something) So, um, how is he?
Buffy: (steps aside to show him that Billy has woken up) He's awake.
Kiddy League Coach: (walks over to Buffy, puzzled) What?
Buffy: You blamed him for losing the game. So you caught up with him afterwards, didn't you?
Kiddy League Coach: (acting innocent) What are you talking about?
Billy: (sits up) You said it was my fault that we lost. (The coach realizes he's been found out and tries to get away — only to be stopped by Giles and Xander, who grab him by the jacket) It wasn't my fault. There's eight other players on the team. You know that. (He lies down)
Buffy: (smiles at Billy) Nice going. (Billy returns the smile as his way of thanking Buffy and telling her 'You did a great job yourself, and I couldn't be more proud')