help me choose – i’m lost

Guys, i’m a newbie . I was dead on buying a s912,and just before the purchase i found this forum out and started reading for about 6-7 hours non stop and now i’m really really lost.

I’m on a budget and i have the following options:

a) S905x with android 6.0 – arround 80 USD Locally – i would of liked Mi box but it’s not available localy and does not ship from Spain to Romania.( no time to order from China)
Beelink MINI MXIII II ( it comes with android 6) – i can also throw in here a custom rom if its going to be better

b) Acer Aspire M1-601 Celeron® J3060 1.6GHz Braswell, 2GB DDR3, 32GB SSD and wifi included – arround 158 USD Locally
c) Intel NUC NUC5PPYH with N3700, 4gb Ram, 64GB SSD – 200USD for Second Hand ( arround 1 year and something warranty)
d) ASRock Beebox N3000 with 8gb Ram, 128 GB SSD – 180USD for Second Hand ( arround 1 year and something warranty)

What i’m looking is – very good / fast / fluid kodi experience. I own 5.1 system trough an AVR and a LG 3D 4k TV.
What would be my best option ??