This question is nearly impossible to answer. Each Person has their preference. ERA is an excellent car. They even offer the Mark II, which is setup for the 427FE motor. However, their cars are not cheap ($54,900 kit) and there is a two-year wait.
CAV is also excellent. I have seen Wayne Presley's CAV car and the workmanship is flawless. You can order just about any color, including the original Gulf colors. Their car only comes as turnkey-minus (you provide the engine). Import regulations prohibit the cars coming in with engines; otherwise they would have to meet EPA regulations.
Roaring Forties is another excellent choice, although I am only going by word of mouth. The kit is offered in various "stages" to help the person who has limited $$$ and can't afford the complete kit all at once.
There are others as well - DRB in Australia, GT40 Replication in New Zealand, and Tornado in the UK.
Bill D