Which installment should I tackle next?
Persona 2 is certainly a great game, but it and P1 are completely different from 3-5. If you want an experience similar to 5, go for either for 4 or 3. Although if you want a more hardcore experience that's more similar to Shin Megami Tensei, the franchise persona was born from, you'd want to try 1 or 2.
Which installment should I tackle next?
First off, I'd like to thank Joker for expanding upon what I said as I know I did leave some info off from my last post. Second, I feel it's important to tell you that 3 and 4 have randomly generated dungeons while 1 and 2 do not, making them more similar to P5 in that aspect.