Each has their own unique qualities and affect. It's also important to find the ones that best suit your needs, in terms of comfort (or discomfort) and sensation that stimulate you individually.
While a vibrator can purposely take you on a joy ride of intense pleasure - a butt plug can tantalize in a more subtle and spontaneous way. For me, using a butt plug works in different "stages" -
1) The first big "wet kiss" where it tantalizingly stretches your ass wider and wider as you're working it in until your ass finally submits to its girth and allows it to enter and find a "seat"
2) The erotic sensation of being "plugged". This is where size, shape, weight, and texture make finding the right plug for your individual tastes is so important.
3) Then comes the plug's subtle nature of ebb and flow. It may calmly let you forget about its presence, then with an unexpected movement - send a delightful wave of pleasure rippling through your sphincter and travels to the adjacent pelvic area. It's can be a constant and random reminder that you are sexual creature and kind of urges you on like a trainer in a boxer's corner. The more sexual activity you engage in, the more actively it encourages you to a higher level.
A vibrator can be less "passive" in its stimulation, requiring less perceptual participation from the user and taking you to your happy place via a more direct path. Obviously this is not a bad thing either.
Therefor, I refuse to choose 😃