Well, my first love will always be a Bernina. I've had mine almost 15 years, still sews like the first day. Now it was a lot of money, but my only purchase for myself from my dad's estate.
I also have a Janome Platinum 760 for classes. Bernina's are still metal inside the plastic housing, so my main machine is very heavy. Janomes are also a good brand.
There's a Yahoo group, SewitsforSale, that has machines listed several times a week for sale. They also have materials, notions, books, etc. I highly recommend it. If I were going to buy another machine, I'd probably start looking in the used market first. Gently used and well maintained. you can get some great machines for considerably less than they originally cost.