An incredibly difficult question to answer.
How much can you afford?
What do you want to do with it?
How far are you prepared to travel?
How many passengers will you want to take?
How often will you want to fly?
Do you buy outright or join a syndicate?
Spamcan or vintage?
What sort of airfield do you want to operate from
But there are some ultralites that might satisfy your criteria; they are cheap, can run on Mogas but you cannot do much in them. And they are not very study, saw two Sportcruisers last w/e without nose legs.
Answer those questions and you might get an answer to your first.
My ultimate reply would be to buy a Bulldog, but then I am biased
However, you try and find one. Even then, they are not cheap to run and will not run on Mogas.