Well many will say the '96 lx or sports. This is because it comes from the factory with a little more power then the previous two ('94-95 lx's) and has most of the "bugs" worked out. The sports also have bigger antisway bars and bigger brakes. It is also easier to do a '99 gt engine transplant into a '96 and is easier to add pi heads. However, i perfer the looks of '94-'95s because they seem a lot smoother then the bubblized '96-'97s My suggestion is to look at both bodystyles and decide which one you like better. Basicly, '95s have a lot less problems then '94s, and are rather plentiful, and '96-'97s tends to be slightly cheaper to mod.
On a side note, a the stock 4.6's will not take a 120 shot of nitrous for very long, making the '99 gt swap a near requirement. Our engines also won't take high psi for very long (above 6psi?) and this could also be cured by a built or '99 gt engine.
(Don't start with a 3.8 v6 bird. It will complicate the engine swap to the point of insanity and high expense.)
On a side note, a the stock 4.6's will not take a 120 shot of nitrous for very long, making the '99 gt swap a near requirement. Our engines also won't take high psi for very long (above 6psi?) and this could also be cured by a built or '99 gt engine.
(Don't start with a 3.8 v6 bird. It will complicate the engine swap to the point of insanity and high expense.)