Should i keep my tier 6 legendary or move up the 9th tier but los powers and usful boosters but also its getting too inexpensive to

Im at an impass...Should i keep my tier 6 legendary or move up the 9th tier epic/rare but los powers and usful boosters but also its getting too inexpensive to keep upgrading.
what should i do?

Also a explaination of how to properly combine items because all ive gotten is garbage most the time.

By the looks of them, you should keep the Legendary items cause they had better stats and more skills.
Better way is use the legendary item for battle and use (wear) the higher epic items when buying in the shop. So you can get newer items and possibly legendary or unique.
Combining items is a waste nowadays unless you are combining legendary or unique items