Is Blocktrail trusted also?
I'm not aware of the first two sites but block.io and blockchain.info are both known and trusted sites but when It comes to the limits that the API provides etc, I believe that Blocktrail is the best choice.
Yes, blocktrail is very trustworthy. Blocktrail.com was recently acquired by BTC.com, which is owned by Bitmain. Bitmain runs multiple pools (BTC.com/AntPool and some others) that handle hundreds of BTC daily, and they also manufacture Antminers.
I'd avoid block.io as there were some accusations that they stole wallet funds (not API) on the forum.