Karnak, "better, best" is too subjective a notion for us to ever agree on. It depends on the circumstances of the given fight.
Speaking from my own experience though I find NIKIs, 109s, Yaks, and Tiffies to be difficult opponents when I am in an LA-7.
NIKIs can out turn me, out stall me, and have a hell of a wallup with those cannons.
109s almost always take the fight vertical and they climb like a fricken rocket so I become the dope on the rope.
Yaks just seem to be much better. They can outturn, out stall, and definately out dive me. They also seem to hold E for ever.
Tiffies just dive away and go until I give up and turn back though I know if they have fuel they will be coming in for another round of BNZ after they get back up to alt.
I think the key difference between myself and some other LA-7 pilots is that I fly the LA-7 more like a spit than a 51/190. By that I mean that I keep in the fight and generally don't extend indefinately and I don't ever do BNZ.
Slap, I was wondering if anyone would agree with me