The best thing I recommend is going to a place that you can try the machine and see how you like them. So start at the brand dealers, not a place like walmart, where they are in the box, and for the love of Bob, avoid those "school machine" sales they advertise in a "weekend blowout"
Bernina is a good brand, I have one, but most because I love our local dealer and I wanted to support her. Other name brand like Janome, Pfaff, Viking Husqurvana and Singer are all just as good, it all depends on how it "feels" to you.
However as that not every wants or can afford a $500 or more machine, I have found a great compromise is Sears. They have Kenmores which I believe are Janome clones. I've had a couple kenmores over the years, and have used more, and they are pretty decent, and they are way cheaper than the name brands.
Things to look for: You definitely want something easy to thread, and change the bobbin. Stitches that are essential: zigzag, straight, and "three step zigzag", and a blind hem. With those you can make anything from a ball gown to a bra and anything in between including home dec, purses and even dog collars. The 3-step is the one to look for.
also important is a 1-step automatic button hole. If you think yo will be making things like shirts, it really is a life saver, to getting everything looking consistent. This is a feature that does effect the price, so only you can decide how important it is.
You also want a machine that has all three needle positions. It can make life so much easier.
and you want a machine that you can get more "feet" for. That's why I love my bernina, but really if you search hard enough you can find the right adapters and generic feet for the basic low shank Kenmores. I have quite a few feet for those too.
other than that all the other fancy stitches are the icing on the cake. I love them on the machine that has them, but they are not essential, and I sewed for a long time without them.
There are lots of other features that are cool, but unless you need them for a certain purpose, they don't matter as much.
If you have any other questions, let me know. I can go on forever and ever about sewing and machines