Depends on what kind of camping you want to focus on and how much money you want to spend. Drive around and visit the camping areas you're thinking about spending the majority of time at. Maybe visit and talk to some of the campers (we love company).
In my case, I wanted to be a full timer, so visited many of the kinds of parks that have the creature comforts I wanted. And those visits showed the majority were either A's or 5th's, so I bought an A. Didn't pull a car for the first 12 years of ownership. Didn't need to, had my bike and used the rig for shopping once per week.
As an example, in the Mexican RV park I'm in right now, there are 5-Class A's, 2-5th Wheels, and one new 25' trailer. Last week we had a fancy B stay here. So there's a 'wisdom of the crowd' thing that help make my decision.
My point is you should buy the rig that fits your intended camping lifestyle. Don't let your current lifestyle choose your rig.