When you get use to work with SSD you will never want see again HDD.
Go for SSD.
I recommend Corsair Force or GT (60GB), Crucial M4 or Intel 520.
I'm using SSD 3 years now in all my machines PC's and Retro (CF Cards)
And i don't want to see again HDD.
No noise,no heat and low power consumption. Go for it. 128GB SSD for Amiga is waste of money and overkill. 30GB-32GB-50GB or 60/64GB is just fine.