This is like asking "what car should I buy?" No can answer this question for you, and the only way you can know for sure is to get on some bikes and ride. Are you into going fast? Going comfortably? Going off-road? A combination of all three? Ride some bikes and buy the one you like the best. The cheaper you start, the more you will have later when/if you decide you want to move into another style or level of bike.

I bought my last car because of the cabin space, split folding seats, actual geared transmission (damn CVTs...) and future resale value. I bought my last road bike because I was looking for the brand, components, frame material, geometry, and projected usage. If you basically don't know what you're looking for then you'd do yourself a huge favor by getting off of bf and hitting an lbs to sit on some bikes