There are 2 distinct classes of loader buckets. There is the light duty material handling bucket which is primarily for moving dirt piles and light duty grading and levelling and will have a single sheet bottom and the heavy duty excavation bucket which will have a double sheet bottom and most likely extra flat gussets on the bottom. Both can come with welded on or replaceable cutting edges but what determines the HD bucket versus the lighter duty bucket will be the bottom sheet or sheets in the case of the HD bucket.
Most people don't realize there are 2 distinct versions and Kubota (and I assume other manufacturers) offer the light duty materials bucket as standard equipment and the HD bucket as an option. I know for a fact that is how Kubota does it and you have to specify which bucket you want when buying a new unit.
If I were you, I'd buy the Kubota bucket as I have one and I've never had an issue with it, very stout and already painted the correct color. I also have the light duty bucket, in fact I own 4 buckets for 2 units. One has my round bale spear installed in it and stays installed.
The other aspect that you don't allude to is, is your unit a 2 handle quick detach or is the bucket a pin on? If it's QD, then you'll need a compatible bucket with the correct spacing for the cam lock handles.