For me it's three.
1.) The Glock.
When they came out, I HATED them, pure and simple. Now, I love them, and own a total of 6. Three in 9 MM, and three in .45 ACP. I couldn't be happier with all of them! They are extremely reliable, built like tanks, are very simple to operate, field strip, and clean. I simply couldn't ask for more out of a defensive pistol.
2.) The AK-47.
Same deal here as well. Couldn't stand the "Cheap Russian things made from equally cheap, inferior parts, by peasants." Now I have a total of 7. All of which run like tops, are fun as hell to shoot, easy to clean, operate, and cheap to feed in spite of todays unusually high ammunition prices.
3.) The AR-15.
I was intrigued by them, but nowhere near enough to buy one. Then the curiosity grew and grew. Finally I took the plunge and bought a Bushmaster A-2. The rest is history. I now own 7 of them. 5 Bushmasters and 2 LWRC piston guns. It really took a lot for me to "crossover" into the military type of weaponry. But now I'm a much happier person for it. It offers up far more shooting possibilities, and with it a lot more fun. And that is why we are all in this gun game to begin with! Bill T.