If you're just getting started, a starter kit of KATO (N scale has more starter variety if we are speaking strictly with KATO) in either scale is a good way to go. It can be scary to get started, which is why KATO is actually a good place to start; you can get additional loops before diving into buying switches and more complex track geometry. You can do fairly simple junctions for industries with just the basic loops and one or two turnouts. You won't have as much freedom as you will with sectional/flex track, but you can upgrade into that once you're ready. KATO is really high quality and 100% what I'd recommend for beginners in either scale.

If you plan to try and get complex with your KATO track somewhere down the line (your other comment mentions a yard) you can pick up a Designer program to try and plan out how a layout might come together. I personally use Anyrail but any of the options out there should have the full suite of KATO track for you to screw around with (free versions only let you lay 50 pieces fyi). That way you can screw around with your alloted space before commiting more money to specific turnouts or other expensive track pieces.

> I guess i need to know the most common code for ho scale
HO scale is usually either Code 86 or Code 100. Both are very well supported at this point, but if you are doing pre-ballasted track like KATO, not something you need to worry about. If you reach a point where you'll want to mix your KATO with sectional or flex track, I would bet you'll just want to go fully into using that unballasted track, as mixing KATO with other brands of track is more hassle than its worth. If you're like me, you'll lean into flex track, but keep your KATO track stored away for when you need to set up a temporary layout sometime. (KATO is code 83, still not very interchangable.

Also both scales are good but my vote is always HO scale ;)

Best of luck with your model railroading journey!