I'm afraid none of us can answer your question adequately any better than you, but my bet would be that your own answers will serve you better if you figure out what you want from your toy train hobby. For example, why are you interested in the larger scale already? What has led you to conclude, so soon, that the other scales have something different, or better, or not so good to offer?
I'm not trying to sound unwelcoming, but you have to start somewhere to get to where you are going. Where are you? Characterize your interest for us. Do you like steam, diesels, long trains, short trains, colourful trains, black locomotives and drab cars, hilly and varied terrain, prairie flat, steam to diesel transition era trains, or modern diesels and excursion steamers? Would you be interested in making a realistic railroad that has pretend revenue work, or do you just like to watch trains run? Would you be content with a large oval and some sidings, or would it be better after a while to have some approximation of the type of switching and train movement like on the real thing?
These are examples of questions you'll need answers to so that we can give you a sense of what skill development you might need, what cash outlay, how much space, what type of tracks and turnouts (switches). Are you thinking you'd be happy in Direct Current train handling (DC voltage), or would you possibly like the more realistic DCC system (Digital Command Control)?
To help you out a bit, when I started four years ago, I knew diddly. I knew which end of a soldering iron to pick up, but a kid would probably have a solid grasp of that by age 6 just by looking at it. I had never done woodwork, never joined two sections of HO rail, never wired up a layout or used a DCC system. I can do it all now, but it came about with trials, patience, a horse-choking chunk of change, some mistakes in purchases, tons of fun and skills development, and now I count myself as a seasoned modeller. Still a long ways to go, but I am content and pleased with my progress. I am sure, with some discussions, visiting local clubs, attending train shows, watching some layout building videos (there are many), reading here and on other forums, you will have a blast. You will grab the wrong end of a soldering iron at least once, but it will be an honest mistake....you were thinking about something else..not long, mind you.
-Crandell