The question of killstreak sheen and effect tiers comes up quite frequently, and while a plethora of opinions can been found there seems to be a dearth of data to backup those opinions. In this article, I will keep opinions to myself and just present data.
The data: At time of writing this article the data itself consists of 386,846 tier 2 (specialized) and 3 (professional) killstreak weapons.
Sheens: If we look at applied sheens irrespective of weapon/quality/australium/killstreak tier we get this:
Specialized and Professional Kits come from 2 sources: Fabricators dropped as MvM rewards or found in certain crates. Assuming all sheen colors have an equal chance of occurring in a fabricator or uncrated kit, the differences above are is due to (a) fabrication of kits, or; (b) destruction (crafting) of killstreak weapons. E.g. More desirable kits might be fabricated more often, and less desirable specialized weapons might be crafted to make professional kits. Less desirable weapons are crafted away quickly and therefore are less likely to be seen by the TF2Tools scanner. So how about focusing the analysis on strange weapons, since they are not able to be used in fabricators?
The outcome is much the same; Team Shine is most applied and Mean Green least applied even when looking at individual classes or weapon slots. However, it has been said that tiers for Australium weapons are different, so let's look at Specialized Australium weapons:
Among Australium weapons there seems to be an increased preference for Deadly Daffodil and Mandarin sheens. Maybe these colors are perceived to match the 'gold' color of Australium weapons well.
Moving on to effects, let's begin with an overall look at all tier 3 weapons:
Since Professional Killstreaks (unlike Specialized) are not crafting ingredients, the differences here will arise from only the most desirable kits being fabricated. Overall, Fire Horns and Flames top the list, Hypno-Beam is bottom of the list. Now if we limit to Australium Weapons:
We might assume that since Australium weapons are very valuable people will endeavour to find a kit they really like rather than apply the first kit they find. Thinking along those lines, let's weed out the lower tier sheens and focus on Deadly Daffodil: