There is NO DOUBT that the sitffleg deadlift, properly done, is the best mass movement for the hams BY FAR!
Problem is almost nobody knows how to do them.
Most reach way down with the arms and have minimal hip pivit.
THE KEY is to pivit at the hip.
This is how you do them......first of all you will need wrist straps once you are working this exercise hard.
Shoulder width grip, both palms facing towards you. Keep the back straight ALL THE TIME. PIVIT at the hip and stick you buttt backwards and bend over. DO NOT reach down with the arms as you bend over AT THE HIP. Keep the bar close to your legs all the time. Legs are very slightly bent(unlocked). A few can do this movement safely with locked knees. Go down ONLY to slightly below the knee and I don't care if you have the flexibilty to put your elbows on the floor. If you go deep you will screw up your back sooner or latter as this opens up the lumber spine way too much.
Before doing each rep take a deep breath and hold it as you go down, stick your chest out and either flatten your low back or slightly arch it...... and then exhale after the sticking point is past on the way up.
Try the movement without a bar.....just pivit at the hip and try to feel the hamstring stretch as you go down. Full stretch occurs somewhere between hands at knee level to hands at mid shin level. Some can go to mid shin but it is risky IMHO.
If you are going down to shoe top level then you are NOT getting more ham stretch but are just reaching down with the arms and rounding the low back...BAD IDEA.
If you are doing them correctly then you should be able to lift almost as much as you squat.
RG