We can certainly help you spend your budget, but we need to know what kind of budget you have before getting ahead of ourselves.
In model railroading, like most anything else, you get what you pay for. If you're looking for something simple, easy to assemble/take down, and not get into the nitty gritty of modeling...then an off the shelf, all-in-one type train set may be the way to go. However, if you're interested in modeling in detail and want a permanent layout, then that's something else. As you can imagine, the budget difference between the two is pretty large.
You've mentioned both Bachmann and Kato, which illustrates my point. In my book, they represent opposite ends of the spectrum in price points. I consider Bachmann to be entry level, and Kato is pretty much top of the line. You're in good hands with the folks here, no one will steer you wrong. But before anyone can really help you, you need to answer a few questions:
1) What kind of budget do I have?
2) Do I have space for a permanent layout, if so, how much?
3) What is my skill level? Do I want ready made structures/scenery, or do I want to model them myself?
4) How much time do I have to invest?
This is just a starting point, mind you. I think many here will tell you that planning ahead and having an idea what you want will save you a lot of money and headaches in the future. Personally, I spent the better part of two years doing research and figuring out what I wanted before making a single purchase.
By being a little more specific in what your needs/wants/goals are, I think you'll find that the fellows here will be able to help you a lot better! Good luck!