Welcome to the board. Everyone is an individual, so there really isn't a single best machine for everyone.
You can get a pretty advanced machine for the money you want to spend, so I would take it slowly. With the number of items you've made, it sounds like you are selling yourself short as to not having much experience. I would start by listing the things you wish your current machine would do: Better lighting? Self threading? Built in thread cutter? Auto Pivot/knee lift? Do you wish you had more room to stuff your project thru the machine arm? Want to do machine embroidery? What projects do you want to do in the future that you think you won't be able to accomplish with your Necchi?
If you have good sales resistance (if not bring a friend who does), take your list and go to a couple of dealers. Sometimes a machine purchase has more to do with the dealer and continuing education and support than the machine itself. If possible try different brands.
Finally, Necchi's are well built great machines. Make sure you keep it for a backup!