In general, they're all really good just for the stat buffs. In terms of individual effects, I'd rank them as such:
Top Tier:
Noah Set (each card gives +Attack, plus the whole set gives a static +10% Attack and a chance to gain super armor after doing any attack--skills included. It's a fantastic set in both PVE and PVP)
Kaya Set (It's insanely good for Defense types, and the effect of granting super armor for five seconds upon tagging is also insanely good in PVP, but also good in PVE)
*Pink Haired Girl Set (I don't remember her name, and this set's only available on the JP/KR servers right now. Basically, the cards all grant +Attack, and the effects of this set are: +12% Attack, a chance to get a +150% damage bonus on landing a skill, and when you reach 1% HP, you gain damage immunity for a short duration, which is the Kazuya/Pretty Brian/Thuganomics Cena core effect. Having that on a battle card set is *insane*, so I declare it top tier)
Mid Tier:
Ryugo Set (This set is better in PVP due to all the effects. +Guard break chance on your skills(each individual hit in a skill has a chance to guard break) and -Attack on enemies that manage to hit you are way better in PVP than in PVE. That said, each card does give you +Attack, so it's good in that regard)
Shine Set (This set's decent for any fighters who are built around crits, like XIV Geese. That said, the Tekken set and the Wonderland Iori set are better suited for crit builds. The chance to get super armor on receiving a crit is annoying in PVP, but not a big deal)
Low Tier:
Ein Set (The effects that this set gives aren't particularly great, in my opinion. Not when compared to nearly every other set. But again, the stat boosts are better than nothing)
