Absolutely do NOT buy any buckets until you decide on what quick coupler you're going to get/use.
Some years ago for my Kobelco SK80, I chose a manual quick coupler called a Klac from Werk-Brau. The advantages were/are: no plumbing, very close mount so no reduction in breakout, to change buckets only have to leave cab once to unlock coupler with simple lever, hookup is done from the cab.
Disadvantages were/are can't reverse the bucket to dig forward.
I then got all my buckets from Werk-Brau with the Klac mount plate installed. It works great.
If I had it to do all over again, I would opt for a hydraulic coupler that would mate with the nordic standard pin bucket system, & buy all my buckets accordingly. And I would seriously consider incorporating a tilt-roto system for maximum versatility. Roto-Tilt & EngCon are 2 brands that come to mine. Yes, it would be more expensive, but you need to think about your tilt-rotor system as a long-term investment that can be switched from your current machine to the one that will replace it. The tilt-roto gives you all the tools to actually do the work, virtually eliminating any hand work. Your excavator is just the power unit to run the tools.