I (personnaly) really like black blades , and serrated blades. However, Sometimes it's better to have a Plain edge than a partially serrated edge, especially at the back of the blade.
Double edge is nice but require extra care and you need to be more safe with it.
Powder Coating (black), can, I guess, help the blade cut better.
And it looks good too !
So, I like black blades. I use to buy cheap knife at Canadian Tire, but man those are dull. DULL.
I just ordered a Becker BK10, and I think it will be nice and sharp this time.
I will give you a steel list to choose from. Normally, 420,420J,440 steel are easy to sharpen but will not keep the cutting edge long, plus it's quite cheap.
You see, when you will see the steel list you will see that a steel is a combonaison of compromise. It's either Sharp longer or easier to sharpen, Either tuffer but easily break, really tuff but wont cut that much...
So, you need to decide what you want in priority.
Here's some list / description of some steel
http://www.zknives.com/knives/articles/knifesteelfaq.shtml
E. What's the "best steel".
Understanding these properties will get you started to fundamentally understanding steels and how choice of steel can effect performance. I often see people asking, what's the best steel? Well, the answer depends so much on what the steel is being used for, and how it's heat-treated, that the questioner can never possibly get an accurate answer. For a knife lover, it's worth spending a little time understanding steel properties -- only by doing so well he really understand what the "best steel" might be for his application.
Check this site, and come back after that