I just did a series of tests for all three F1 cars you've made. Here's the results:
1. Lotus 78. The best handling. However it's downforce gives it a top speed handicap.
2. Tyrrell P34. The easiest to drive, and the fastest. But it has two flaws. 1st, it understeers quite a bit. and 2nd, it has a noticeable amount of front lift at high speed, further contributing to it's understeer while making it extremely stable.
3. Ferrari 312t. This car is a complete nightmare to drive. It's only merit is it's acceleration.