As far as folders go recommend you go to Sportsman's Or Gander or someplace and hold a few, try them out. You might like the assisted opening or hate it and there are numerous choices even in the design of that feature that may feel awkward or may feel natural. There a couple styles that require monkey fingers to operate IMO and are slower to open than a non-assisted. Some folks can't stand liner locks or might dislike the grip material once they feel it. Blade design/shape is a very personal thing and will likely be a major factor in your decision. Personally I wouldn't own a Spyderco but that's not to imply there is a thing wrong with them I just don't like them, same as some folks don't like Glocks (no really!) though I am a huge fan of Benchmade for example.

Usually well-known brands are a fairly safe bet, the quality of a knife is tied up in the steel used and the construction. Among other things grip materials, where it was made (US or import) influence the price and be an indicator quality as well. Just like cars, stereos or anything else many of the "top" brands command a premium due to their popularity and in the strictest sense are over-priced for what they are but many folks will pay it to have the "coolest" thing. YMMV but there are many very fine blades produced by custom makers and some of the more mainstream brands such as Buck.

Unfortunately I've never been able to settle on a single knife EDC or otherwise and you will probably end up with a drawer full like most of the rest of us. Personally I currently carry a CRKT Ignitor T most days (an inexpensive EDC) but various other knives depending on what I plan to do that day.

edit: one other thing to consider is where/what you are doing. I never carry expensive knives when I'm doing construction or electrical work as they tend to get lost. Seems minor but I have lost a ton of knives that way and it does influence what I carry.