I've owned an HP (my first PC), an Alienware (that I bought in 2006 that's still kicking, although not "current"), and a Dell. My father owns both an HP desktop and an Acer laptop.
My HP endured years of straight up abuse and torture from me and still managed to last a good long time. Not the easiest machine to work on though. My Alienware has been flat out amazing since the start. The Acer my father bought back in 2007 is never a speed demon even on the best of days. On the worst, it feels downright slow. I keep that machine tweaked up and in shape to the best of my ability like I would my own. My Dell laptop? I held out on buying from Dell for a long time, but eventually decided to give them a try. Glad I did. The machine has really been quite amazing! Yes, it cost more than the Acer, but I have really gotten a lot more out of it. If Acer really wants to beat HP and Dell, they need to do a bit more improvement on their build quality, and remove the massive crapload of junk software they preload onto their machines. I was afraid of that with the Dell, but guess what? It didn't come with junk! They've apparently learned their lesson.
PS - Oh, and I think Acer needs a new slogan. There's still no beating the good old fashioned "Dude, you're getting a Dell!"