Bootstrapping from only BLK*.dat which is quicker?

I only have BLK*.dat and is looking to bootstrap a full node.

What is quicker?

bitcoind -dbcache=16000 -reindex? (the blk*.dat is already copied to datadir of local HDD.)

bitcoind -dbcache=16000 -loadblock? (the blk*.dat is still on the external HDD.)