There are 2 parts to your question;
1.Important for performance or...
2.Important for just riding?

1.Light stiff wheels will make a noticeable difference and a rigid frame
2.Definitely get the right saddle/seat post, cockpit and sort out your riding position to maximise your comfort.

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It's not how much you spend on a bike it's how hard you can ride it.

regarding pedals. I've had the top of the range and near the bottom of the range pedals by the same company and have noticed ZERO difference. Not sure what you guys who suggested pedals mean that it is important for a build.

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It's not how much you spend on a bike it's how hard you can ride it.

That's a great distinction. I probably meant both in the same word. However since I already solved half of (1) by choosing a well-accepted frame that fit my budget, this becomes non-issue. For wheels, the Bike will come with Ksyrium Equippe and Conti 4000 tyres. I have to ride them first to see how I like it. But since the completed Canyon bike is so cheap I can sell the wheels without much concern for overall budget for the bike should I want to change them.

As for the Pedal issue, I have learnt from you guys and elsewhere that for decent manufactures, going up the price range is generally for lighter weight. Since this means a real money sink, I opt for a value, and dependable pedal (Shimano 105 SPD-SL). This should be more than good enough for me.

Thanks for all suggestion.

Just because a frame is "well-accepted" and very much bang for the buck, it doesn't mean it's the best choice for You. There is alot more to a frame than value and performance, don't forget that. Many people, on WW in particular, already has.

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Roadbike
Kinesis RaceLight T2

Mountainbike
Van Nicholas Zion Ti

Most important criteria for frame (1 is most important):

1) weight
2) looks
3) stiffness
4) lateral compliance
5) fit

Well, at least for the partially fashion weenie leaning members of Weight Weenies. Some people might consider fit to be the most important - don't listen to them, they probably spend too much time riding and not enough time on the internet commenting on the looks of bicycles.