"~can I consider one filter to be better than another"
Yes, you're correctly on to the first and most basic comparison: media volume.. a nice big thick bed of any type of media is better than a few pieces of it or a thin amount of it - makes common sense to most people and is right (with the rare exception of a media getting too packed down and causing the flow through of water to be too slow.)
The second factor (staying general here for learning) is the "fit" of the media in its container. We don't water to be able to "cheat" and find pathways through the media such that it doesn't pass close enough to the media obstructions to allow them to do their thing and stop particles or process substances. (mechanical media simply traps particles, chemical media grabs particles via plus/minus charge and biological media of course means each little bacterial cell takes in a substance, does a complicated chemical process on it and then gives off something else.) So for "fit" you don't want your media leaky or too tight. In a good filter design you will see that the designer has thought about this!
Beyond this you get into more and more comparison factors that I could write paragraphs and paragraphs about. For instance, the little pipe that sprays the pumped water down on top of the media.. well that's fine but the tradeoff there is noise, its going to inevitably create some water noise (pure internals and external cannisters avoid this by keeping all operations submerged at all times, whereas HOBs, "quasi-HOBs" like yours and Sumps all have water noise.) So I'll leave off the comparison and move on to your mature media question..
All media, or most media I should say, perform an overlap of functions: for example, carbon chunks have chemical (charge based) filtration as their primary function but they will also harbor a fair number of bacteria on their surfaces acting as a mediocre biological media. What this means is that virtually all media can conceivably have some seeding benefit if moved to a less mature or new filter. Still, seeding is always all about biological media and getting bacteria, so moving the *biological* media is best. In less expensive filters the sponges are the primary biological media whereas in large expensive filters the ceramics will carry probably more than the sponges. As we know, both of these compete as the very top biological surface devices. Ceramics like rings/noodles are also great at randomizing the water flow and helping with large particle trapping. As the mechanical sieve function grows smaller, sponges quickly win out and finally of course one must resort to floss or floss pads for the finest of particles (short of super high-tech membranes and pressurized force like an RO unit uses to take minerals out of water!) All of this is to say that if you are aware of it you may have more options for seeding than you might at first guess.
But still, the primary best practice is to either use scissors to cut sponges or simply divide and take some of your ceramics. The golden rule (at least from my reading here and elsewhere) is that you can remove up to 1/3 of your biomedia safely. The 2/3 that remains, if the media was mature of course, should regrow with minimal chance of a mini-cycle in the donor tank.
Well, in my attempt to catch the teachable moment I may have gone on in too general a manner. Sorry! Hopefully it will give you the tools for a good choice someday or else others who may have actually done a transfer from your actual model of filter (my personal experience is limited to Eheims, Aquaclears and simple filters.) I also may have missed some of your questions...
~~waterdrop~~
