MI BOX VS HTPC VS NVIDIA SHIELD

Hello, Greetings to all in my 1 post.

I am old MCE user and after mediaportal, and after dying my htpc I will change to kodi.

I’m looking for a new player.

I have;

—- Old homecinema without hdmi, optical input and spidf, “no hdmi”.

—- Tv fullhd, hdmi

—- HD Projector, hdmi

After reading the great guides, these are my alternatives:

1. XIAOMI MI BOX: € 80. Fan of Xiaomi, apparently a great device http://forum.kodi.tv/showthread.php?tid=275083.
It speaks very well, but.
Is the audio output digital?
Can I connect the jack output to coaxial or spidf?

2. Htpc: € 175-275
Update my htpc, I only have the box and a tv tuner.
My idea: Intel Apollo

J4205 vs J3455 Is it worth the J4205? I will not play 4k

3. Nvidia Shield. € 200
This is my last option

Thank you, sorry for my English