This subejct has been covered many times over and there are as many opinions about it as there are members on here!
I will try to outline the concensus in a non-biased POV. Just FYI, the same principles apply to most of the mods on the blaster... so pay close attention.
The answer to your question really depends on a few factors, mainly: your budget, eventual power goals, and how much you enjoy fiddling with your blaster....
First off, reeds don't add lots of power. There are other factors which limit the maximum flow through the engine, only in the MOST extreme cases (full on drag bike trying to run factory reeds and factory cage with stops) would reeds actually limit power output. What changing the reeds does, however, is tune throttle response to your riding style. Aftermarket reeds "crispen" your throttle when added with other power additions.
Reeds are a wear item, they have to snap open and closed really fast and their design is a trade-off. Yamaha did not want a bunch of owners coming back with 20 hours on their quads complaining they wouldn't start so they put stiff reed petals in them so they would last a long time before they needed replacement. Unfortunately, reeds also need to be able to open and close quickly and stiff = heavy and they don't move as fast.
Boyeson developed a reed material which is lighter than factory and NEARLY as strong. The power series reeds are single stage (just like factory) but move a little quicker so they are a little "crisper" than the factory reeds. The disadvantage is they "banana" quicker so they will need replacing sooner.
Boyesen also sells the pro series reeds which are a generational leap in technology. They are a dual stage reed, a large petal which opens both but a small petal which only opens itself. At low flow the stiff large reed stays closed while the smaller, lighter, less stiff petal opens and closes very quickly. Usually the inner reed is made of carbon fiber to keep it strong to resist "banana"ing while allowing it to be light and open and close quickly.
Then there are replacement reed blocks; the boyesen "rad" valve and the moto tassinari "vforce" series reeds. They both have advantages and disadvantages...
The v-force reeds are a replacement reed block only with 4 reed surfaces (instead of the stock 2) and carbon fiber reeds. The housings are injection molded plastic and notorious for leaking even when properly gasketed. They are expensive (~$150) and you still have to run an intake manifold.
The boyesen rad valve has a whole replacement intake and reed block together cast out of aluminum utilizing boyesen reeds. The rad valve for the blaster is fairly restrictive in it's stock form as it's designed for "torque" applications. With some work, the rad valve can flow more than the factory reed block and I like that it completely replaces the reed block and intake manifold.
Warning: personal preferences to follow!
Personally I think both the VF3 and Rad valve are too expensive for the advantages they give and disadvantages they have... I like the dual stage reeds from boyesen for the power vs. price they offer. That's what I run in my quad.