As 2dogs says, you'll get a lot of opinions. There are, of course, a good number of advantages and disadvantages to each option. The 998 is a great motor, and if ridden as designed, will keep up with the 1330 no problem.
Without going into a great deal of tedious text. My simple advise is, if you are sure you are going to like the Spyder and keep it for a good length of time, and you can afford it. Look for a later model.
If, however, you are not 100% sold on the concept and you're testing the waters to see if a Spyder is right for you, then the 998 models become much more inviting. Because these are great machines in their own right. I'm still riding my 2008 GS and loving it.
With an older 998 model, you can get into the platform for well less than 1/2 the money. If you change your mind or decide to move up to a later model, you can usually get your money back out of the original purchase.
The 2 that I would avoid would be the 2010 and 2013 RT as BRP cut corners on these 2 models. Though with some upgrades, these can be just as good as any others.
Good luck in your quest!