As per our post on OpenCollective, Please post your suggestions here 
Thats great news.
I would very much appreciate, if you like to set up the NAS and to include NAS-related questions to your support.
Concerning your Question: I don’t have any drive related questions (for now). I myself use WesternDigital WE Red drives. I assume - to run dockers on the NAS you don’t actually need huge (capacity) drives.
Concerning the SSD (to be used as cache): it is recommended to only use the SSD´s recommended by Synology.
If your Synology NAS is up and running, I would very much be interested to get your help for the following containers:
-> calibre
-> Booksonic
Yours
Henning
A good practice is to use a mix of drive models and batches (i.e. never buy a bunch of the same drive made at the same time).
I use a couple WD reds and a couple seagate ironwolf hdds
really looking forward to getting first-class support on synology devices!