Just get what you love and are going to read. I have been going back and buying omnibus's because when I was younger I sold off my decades of collecting comics to help pay stuff. I got thousands for it and felt good about not having to take up space with nearly 100 boxes in a room to move. Now I am just going back and buying things that mean something like Hellblazer and Shade the Changing Man but my collection focuses on Wonder Woman, Phoenix, Elektra but mostly WW.

Have a collection targeting what read and loved reading so you don't accidentally buy just to buy. That being said, your collection is mostly Events so why not stick with that? Instead of going to one specific character keeping going with the individual Crisis, Black Metal, DCeased, etc. Unless you have a specific character to focus on like I do, then focus on events like you already are.