ducklord wrote:What is the recommended combination?
There are a lot of factors that play into this. Each player will have a different game-state and play-style. The answer to this will imply a lot of, "if you do," statements. "If you buy a lot of commons and flawless," "if you can craft a lot of items quickly," "if you can quest for your own artifacts," "if you create your own components," "if you are willing to gamble," "if you are lucky with your gambles," "if you are willing to spend the time," "if you have 4 simultaneous fusions," and so on.
Common + Flawless uses less Flawless items as inputs (and generates Flawless at outputs), but requires more Fusions than using flat Flawless only. The other consideration is that Common + Flawless requires commons, and for a majority of items up to level 15, the progress bonuses make the items always craft as Good or Great. If you want to gamble, you can use less Epics. Fuse times are less of a consideration for low level items, and are a much greater consideration for higher level items. It is sometimes much faster to craft 25 Flawless items and do 5 fusions than it would be to craft 10 Flawless items, then do 16 fusions.
If you have difficulty acquiring Flawless items, you can craft the target item and fuse together your Goods into Greats and Greats into Flawless. It takes time, but requires much fewer crafts. It is also much less wasteful if you are spending difficult to obtain artifacts and components.
TL;DR: For low level Legendaries (level 15 and lower): I recommend fusing non-identical items for faster fusions. I recommend fusing Greats into Flawless. I recommend fusing 5 Flawless, 5 times. I recommend 5 Epics into 1 Legendary.