The best car handling I think is V1 RRR WC. It's the current world champ. Why buy RD logic ? This car is same as Team Magic G4 ( the original car ). In my home track, G4, RRR, 710 are frequent winning cars.
The best engine ? It depends how much money you are willing to spend. JP, Max, IDM, RB are premium modified engines. If you don't want to spent too much, Novarossi N12LL5, NSR12S5, OS TZ5 are respectable engines too. There is no point to risk yourself from buying second hand or cheap engine. You could always buy complete set P/S/R to renew engine life.
Dragon makes good point. If your LHS have a car of your choice and tons of spare parts, you are set
You need good FM/PCM radio gears like Sanwa M8 or M11, Ko Propo Helios, Futaba 3PK. You don't want to chase nitro cars
You need metal gear servos, preferably over 8kg of torque for steering and brake/throtle. Currently I'm using 13kg servos KO Propo for durability reason. I have overkill 24kg servos from Hitec 5955TG
but those are reserved for MTX4
You also need nitro friends to help you break in and setting the engine.
Nitro cars are more satisfying to drive.