1. Leonardt Principal
This is my absolute go-to for all scripts and the nib that I suggest for beginners. Its flexibility allows for dramatic swells, fine hairlines, and trains you to keep the light touch we all intuitively have. While it may be hard to control for beginners, my opinion is that it is worth it even if you end up breaking it. While G nibs (a more popular beginner nib) are more forgiving, they require more pressure and if you get accustomed to that pressure, it becomes hard to gain back a light touch.
2. Gillott 303
This smaller nib allows you to create finer hairlines and decent shades. I think of it as my mini Leonardt Principal. The modern day version can be a little catchy on the upstrokes but its pros outweighs this. I mainly use this for Spencerian and Engrosser's Script.
3. Brause Rose Nib
This nib creates huge swells and decent hairlines for the size. I usually use this for Ornamental Script on envelopes or where larger writing is required. It can be hard to get the ink flowing on this one so it's good to have a piece of scrap paper nearby so you can "poke"/"stab" one point to get it started.
4. Gillot 1068a
This nib is less flexible than the above but is amazing for Engrossing. Master Penman William A. Lilly uses this nib exclusively.
Please do not let the above list stop you from trying other nibs. It is always good to browse and test them out for yourself. We all write differently so you may appreciate other nibs more than some of the above. I say that nibs are like shoes. These are my favorite Louboutins. Go discover yours ;)