Don't smoke store-bought blends.
You wanna know about which cannabinoids are hot on the market right now, in US\UK areas?
5F-AKB48\AKB-48
UR-144\5F-UR144
They're all legal, and they get the job done. They're probably what's in your blends. (unless AM-2201 is still legal in the UK? If it is, then you're probably getting a lot of that crap...sorry)
The URs are pretty cerebral (5F variant too much so) with shortish effects and no real side effects.
The AKBs (and the related STS-135\2NE1) tend to have more side effects, although in specific populations. They also have a better, more thorough and long lasting high.
I use 5F-AKB48, UR-144 and MN-18 on a daily basis, both medicinally and recreationally. No ill effects to report of here - although I never smoke blends, I only use the pure chemicals.
Before JWH-122 was banned, that was my go-to cannabinoid, but that's not on the shelves anymore.
Before JWH-018\073 were banned, those were my "go-to"s, in combination.
If you have any more specific questions, feel free to ask, I'm kind of a synthetic cannabinoid connoisseur. As far as making a list of all cannabinoids and effects goes - it would be quite lengthy, and most of it would be obsolete, since the vast majority of the 'oldies' are now either explicitly illegal, or subjectively so under an analogue clause.
I'll give you a quick run down of what's available today though:
MAM-2201: Potent, and long lasting. A stoned-ness in the forehead is present, but some 'rushing' as well, although nowhere nearly as much (and that's a good thing) as it's para-demethylated predecessor, AM-2201.
AKB-48: Stoney, almost exclusively so. Long lasting, not quite as potent as I would like. Similar to JWH-073 or JWH-200.
5F-AKB48 Stoney and uplifting, a bit shorter than it's unfluorinated sister but more potent in exchange. The superior of the two, IMO.
UR-144: Cerebral and soaring. Similar to JWH-250, in both effects and duration.
5F-UR144: All of the negatives of AM-2201 with none of the 'fun'. Very short(20mins), a kind of disorienting paranoid express ride in futility. VERY potent, however, and cheap - which is why I imagine commercial blends seem to have gotten even shittier. Quite good though (in TINY amounts) as a mixer with others, like AKB-48.
STS-135: Light. Hard to tell...I haven't run any PET tests obviously but if I had to hazard a guess, this one would be a partial agonist. Feels as if somethings missing. Large amounts don't counter this - rather they only add to the alienation. Miles better than 5F-UR144, but still not my favorite. Some people enjoy it, however.
MN-18: A little less potent, and a little shorter, than JWH-122. Otherwise, really itches that same spot. Unfortunately, tolerance seems to rise a lot quicker to this than with the oldies - best left to a once in a while thing.