Perfect topic for a thread, since there is no one right answer!
It's about personality this, some like quality over quantity, I´m more of a quality kind of a guy. I started this hobby in my teens way back in the mid 80s. I´ve had a few different airguns over the years. But mostly its been pistols, since I find them very practical. They can be enjoyed at short distances and are easy to bring to places where you can shoot. My all time favorite is the Webley Tempest, perhaps mostly for sentimental reasons (I´ve had a few). I also have a Beeman P2 and HW45. Last decade I bought my first match pistol, a FWB 102. But it did not do any good for my elbow when I cocked it. So it was sold and a Tau 7 added, now this is a sweet gun! And really cheap here in Sweden (as is FWB´s). My Tau is a keeper! I also have a RWS 6M, but it is just a collectors piece for me (nearly mint), it does not fit my hand at all. I´m very intrigued by the recoilless action though! And then there´s a few project guns laying around; an old Premier (maybe a future favorite), RWS 5, Walther LP3 ...
I like my Tau and Webley the most, they are both perfect for what they were meant to be, match shooting and plinking respectively..
I like rifles just too. On had is a FWB300s (It´s my all time favorite airgun of all) and a AA TX200. And of course my old Webley Tracker in .22 (5.6mm). It is hard to find ammo for it that fits the old British .22 bore, but I´ll hang on to it as it is still legal to own w/o a permit, due to the "grandfather law". And it is a good gun for what it is, even though it is very 'old school'.
Personally I feel I have too many pistols, most see very little use. But selling them would not make me rich... I Would like to add a few rifles though. A HW30 and a couple of PCPs would be useful, one high power and one for FT type plinking.
So in summary three rifles and three pistols would feel OK as a bare minimum, five or six each much better! I prefer mid range optics like Burris, Weaver and Leupold, I find decent optics to be a large part of the enjoyment. And that brings down the number of guns I will own due to cost. I´m actually very happy as it is now!