Can somebody help me understand what type of seat I can expect when I'm travelling in business class on SQ?

I recently switched to SQ from BA and am rather disappointed.

On a SIN-DEL red eye the business class consisted of a 2-2-2 configuration with seats that converted into a slope. The plane looked seriously old. No USB charging ports.

On a SIN-CPH flight the seats were a little more comfortable and the back of seat pulled down to make a flat bed. You had to curl up to get comfortable but it worked. No USB charging ports.

On a LHR-SIN flight we had what looked like a new plane with comfortable seats that converted into a flat bed. The seat type was different from the two above and was identical to a Cathay business class seat.

Why do SQ have three different types of seat in business?

Frankly the only one worth actually paying for is the new Cathay style one.