What is the best way to share the blockchain and get it verified by the wallet? I am the owner of BlockchainDownload and am looking for a way to get some trust in the website.

I have shared the link in a couple of topics an get the response "Please do not suggest that people download a preindexed blockchain from you. Doing so implies they need to trust you to tell them exactly how much money everyone owns.".

I do now generate a .rar with the whole data directory exept of the peers.dat and wallet.dat.

Is there a way to share the blockchain on a more trustworthy way?
You can literally concatenate all the *.dat files and share that. The user downloading can use that as their base download by using the bootstrapping option (-loadblock) in bitcoin core.

Generally, the trust a user puts in the blocks you give them is not really needed since the proof-of-work is verifiable by the new node. New blocks will also reference the previous block so it's easy enough to verify that they're on the chain that new blocks are coming in from.