It definitely used to be Turkish Airlines until about 4 years ago. All ET tickets in Y used to credit 100% to Turkish where 40,000 miles were enough for a 2-year *Gold. Unfortunately they stopped this.
If you occasionally travel in business class, then you should be aware that most of ET's available and cheapest business class fares are in P-class which credits 0 miles to most FF programs except their own Shebamiles.

Besides from your target to become *Gold I would sincerely suggest you look at ET's Shebamiles. While it might not be an easy way to obtain gold without occasionally flying in business class, they have very good redemption rates of miles. Meaning you can fairly cheaply upgrade yourself to business class on a range of long flights for a maybe 25-35,000 miles. Also, as ET Silver you have access to a dedicated silver lounge in Addis. But granted - I have no idea what it looks like on the inside.

On a side note: I find that one of the main features as *Gold on ET is that they automatically block the seat next to you unless flight is fully booked. Meaning that you will rarely in economy end up with a person next to you, unless flight is full. It works much(!) better than the new function they have that allows you to purchase an empty seat.

I entered the main lounge in KGL twice as *Gold in the past 6 weeks without any issues.