Best training I have been through was Horizon. I have been through 2 regionals, 2 national sized carriers and 1 independent to get a type rating. Horizon was great for a first timer hitting the airlines. A friend recently went through and he said it was very long but they covered everything. Some others I did were self taught for the most part.

The best thing you can have is someone that knows the airplane inside and out. A former carrier (now out of business) had a guy that had 10's of thousands of hours on the equip and he could trouble shoot problems at 3 am over the phone, and give us ideas on how to get things working again with out the help of a computer or manuals. It sure helped always having a PFE/mechanic onboard! He taught the airplane so well he could practically build the damn thing (A-300)!