Saw pulp fiction first, not long after it came out IIRC. I think it's a great movie, and at the time I was particularly impressed by the style. I was still a kid and had only seen really mainstream movies, so it was unlike anything else I'd ever seen.
Saw reservoir dogs a bit later when I was around 18, and was really impressed with it. Those two movies made Tarantino someone to watch for me.
I remember a lot of people really seemed to like the kill Bill movies at the time. Not sure if people have changed their minds on further viewings, or if an entirely new audience was just unimpressed with them. I think they're great movies and represent Tarantino at his absolute peak. There's such a mad blend of styles and genres in those movies that they probably shouldn't work, but I think they're great. I don't own a lot of movies, but I have all of those on DVD somewhere.
RD will always be the ultimate heist movie to me. I've seen that one so many times over the years and it just gets better and better. Really tight, minimalist, focused storytelling. Especially for a guy like Tarantino that tends to go overboard on gore or stylistic elements.
Also never saw the hateful eight when it came out, but it's on Netflix and I watched it several times recently. It's pretty great imo and I would put it on the level of his earlier works. A spare, gritty, tense, spiteful little film. I enjoyed it a lot more than I expected to.