Certified - AndroidTV Device Comparison Table (click)
Beware not all devices are approved to install or even stream HD or greater Netflix.
If you do not need Netflix, the Best bang for the buck from that table is the Mecool KM3. (Faster vs the Mi Boxes / Jetstream 4K Ultra)
The best bang for the Buck device that streams Netflix, Prime Video etc. and runs Kodi is the FireTV Stick4K - especially when it on discount sale. That has the best wireless remote going around as well.
Read the following FireTV 4K post and take note of the minor stuff that does not quite work properly with Kodi:
https://forum.kodi.tv/showthread.php?tid=336151
The very soon to be released Amazon 2019 FireTV Cube will be an even more powerful beastie with an even faster high spec AMLogic S922Z chipset in it.
Als be aware the Amazon devices have properly implemented Dolby Audio Licences, which is important if you have old audio equiptment that does not support EAC3/DD+ audio and you still want 5.1 audio from Netflix & Prime Video type streaming Apps.
Both devices will have better picture quality vs the Shield. The Shields old, but still fast GPU has never been know for great upscaled picture output quality vs the more modern competition. It also has no Dolby Audio Licence, which can cause issues with older audio equiptment.
Home network 4K HDR Bluray Rips video streaming needs Gigabit Ethernet, or you add an ASIX chipset USB3 > Gigabit adapter, like the Ugreen ones to devices that do not have GigaE.