How old is your dog? I like Trupanion for puppies (under 1 year), and went with it for my puppy. If you do opt to do with Trupanion, ask your vet about the vet exam voucher, which gives you a 6% discount for premiums.
I have VPI for Camper. I don't particularly like it. For illnesses, I haven't found it useful at all (they denied my claim for contrived reasons). I'm at renewal now, and I'm trying to decide if I should renew it with the mindset that it would be helpful for major catastrophic situations, like injuries. I wouldn't count on it for illness. I haven't decided yet.