For your 20s, definitely Azzaro. Paco Rabanne just is a bit too mature and less versatile than Azzaro, which you can wear in most any situation. I'd be more comfortable wearing Azzaro than Paco by a longshot (I'm 26). Considering though that both can be acquired fairly cheaply, if you're a fan of both no reason why you can't have both in your collection since they're completely different scents
Depends on where "here" is. In the US you can purchase a full bottle for ~$25, but in other countries it might be significantly more rare. To this day Azzaro PH is the only fragrance my dad will wear and prior to the internet, he would hoard bottles from whatever store he could find them in and pay a premium price because it was so difficult to find and he could never be sure when he'd be able to find it again. He still has a number of those bottles that are unopened and unused. I don't believe Azzaro PH has ever been reformulated but if so, he has a number of bottles from the mid and late 90s that could be worth something
Paco Rabanne PH shares many similarities with Azzaro PH. It's just that, IMO, Azzaro is so much better. I would basically describe Paco Rabanne as Azzaro with a greaner opening, while exihibiting a "soapiness" throughout its lifespan, a soapiness that I just don't get from Azzaro. I don't find either to be dated. Paco Rabanne is a good fragrance. However IMO, Azzaro PH is a GREAT fragrance, certainly in my top 5.
You really NEED to get both, but if you are a huge fan of Brut(as your avatar suggests) you may like Paco a little better. I like Azzaro better myself, and it may be the best mens fragrance ever(not my favorite but its up there). Paco is more bright, green, and soapy than Azzaro. Azzaro is darker, more complex smelling, and I think more versatile than Paco. Also $80 is way to much for a bottle of Azzaro.
I agree that $80 is too much to pay for a bottle of Azzaro PH. Not because it's not a great fragrance (because it is), but rather, because you can buy it for MUCH, MUCH cheaper ($20.00 for 1.7 EDT, $30.00 for 3.4 EDT at a number of discount stores - TJ Maxx, Marshalls, Ross, etc.) Why pay $80.00 when you can get it for so much cheaper??
One more for ApH. While on the topic though, I think a lot of the reason PRpH isn't as popular as it could be.. is because of its flaws. ApH is smooth all the way through, while PR is a little bit "rough around the edges" so to speak. What bugs me most about it, is that nasty plastic smelling sharp accord that dominates some of the top and most of the middle. It's unfortunate, because it smells amazing aside from that.
These are two different fragrances and the only similarity they share is their unique personality and character that deserves respect.
AzPH starts off with a riot of colours whereas PRPH starts linear. AzPH then becomes linear and it's hard to make out the middle notes from the base notes. With PRPH the dry down is sophisticated and mature (in a smoky, dark kind of way) yet it manages to stay green.