I used medictests for my NREMT-P recently. I found it to be kind of mediocre. The best site I've seen so far is JB Learning's "Navigate Test Prep".
What I've seen of FISDAP was also very impressive but I haven't seen much of it. Looking at their website, it's a bit unclear how much material is there... It says you get a 200 question practice exam, and can take quizzes... But are the quizzes just randomly formulated from the bank of 200 practice exam questions?