Basically... it comes down to which one you need: clearness or price. The ClearFLEX is half of what the Tygon is, so it really depends. Like the ClearFLEX works great for me - I got UV gunk in my water anyways, so it's not like it will glow any brighter. 
So, really comes down to personal preference.
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Mario
XP 1600+ @ XP 2200+
1 GB of PC2700 Crucial
GeForce3 Ti200 @ 220/500
GIGABYTE 7VRXP rev 1.1
30 GB HD
CDRW
Aircooled