TCP socket: Blocking or non-blocking?

Question

I am writing a PC application that will connect with TCP to multiple micro-controller boards. The micro-controller boards are listening and the PC app connecting to each of them as a client.

There can be up to up to about 50 boards depending on configuration, and it is not clear to me if it is best to create all these sockets as blocking in individual threads waiting at recv() or make the sockets non-blocking and use select() to check for incoming data one socket at the time.

So is up to 50 threads of blocking recv() OK, or is it better to check one socket at the time with select()?

Info: Data is almost entirely coming from the micro-controller boards and the rate can vary from essentially nothing to max. of the network.

Thanks...