from my understanding, the Q5 uses a wrapper to play from kodi, so that it uses himedias own video player, otherwise the image quality will be blurier (something about kodi not supporting hisilicon chip?)
The Q5 uses a Mali-450 GPU, which is fullly supported in hardware by Kodi. The reason people use a wrapper is because features like 3D-ISO and 7.1 audio are not supported by Kodi, so you need the wrapper (which does indeed use Himedia's Android player for playback). Image quality in Kodi without wrapper is very good, the same as other boxes with Mali-450 like MiniX X8-H, Wetek Core etc. With wrapper installed, however, image quality is much better because it uses the Hisilicon custom hardware image enhancement engine (ExpressXEngine). This gives better contrast/sharpness to the extent that on various forums it's been called the best you can get and comparable to the top end Oppo Blu-Ray players.
Downside from using the wrapper is less kodi support for some features, particularly kodi apps.
This can be a problem, although it is minimal because the wrapper is only used for certain formats and not streams. There are a few threads in the Q5 section about customising playercorefactory (the file that initialises the wrapper) to further improve this.
Whereas i heard the H8 doesn't use a wrapper. But this come at a downside of default blurier video quality? Also will i still be able to use a different video player e.g. MXPlayer, or will i be stuck with kodi's default video player?
H8 image quality is comparable to other high-end Android boxes. It's certainly not blurry!
You can use MXPlayer is you can find/write a custom playercorefactory to call MXPlayer from Kodi. Kodi doesn't have easy set up for external players, it needs coding.See here: http://kodi.wiki/view/HOW-TO:Use_external_players_on_Android
Also any issues with the kodi apps on the H8?
Not that I know of.
PS: looked at the spec sheet, the H8 has 100mbit ethernet, whereas the Q5 has 1gigabit ethernet. So doesn't that automatically mean the Q5 is the better deal?
It doesn't make much diffeerence. Video content will never go beyond ~70Mbs, even for 4K, and both 10/100 and Gigabit can handle this. There are also usually other bottlenecks in media boxes that inhibit maximum speed before you get to the limit of Ethernet bandwidth. In my opinion, Gigabit is still more a marketing thing in media boxes. I know many people will disagree with this.
