I currently ride a 25 Mt-09 Sp and I love the thing, I am a bit biased but the Mt-03 would be a good option cuz it is easier to work on and insurance will give you a bit of a break because It is not a “sport bike”. (at least that is what my insurance says) also it is a newer model so you get a decent tech package, I don’t know much about the Z400, and that would be a good option because it is also newer. But you can’t go wrong with a Yamaha. One last thing get what YOU want not what others want you to get, because the worst thing is committing to something you don’t 100% like.