Squats were easier because you didn't tire them out before you trained them. Nice work.
For the "stiffs" - how are you doing them? I see a lot of things at the gym that people think are stiffs when in fact they're badly-executed straight leg deads. For stiffs, the legs are softly straight but stiff in that position, the barbell is pushed into the body the whole way down AND the whole way up, and you only lower until you feel your form start to deteriorate - that is to say, until you realize you can no longer keep your back tight and straight. Then you reverse it and stand.
If they look like this, you're good.
If they look like this, I'd suggest changing your form.
Another small suggestion I offer you is to structure your workouts so you hit the heavy compounds (that means multi-joint) lifts first. For example, squats, deads, bench press, and rows are all heavy compounds. Leg extensions and bicep curls are isolation/concentration movements, for one muscle or one part of a movement pattern.
So for your workout, you did:
BP - compound (horizontal press)
leg ext - isolation (quad dominant accessory work)
crunches isolation (core)
Bent rows - compound (horizontal pull)
hams - isolation (ham dominant accessory work)
overhead press - compound (vertical push)
squat - compound (quad dominant)
stiff leg dead - compound (ham dominant)
Ideally you will hit ham dominant, quad dominant, horizontal pushing and pulling and vertical pushing and pulling in your workouts - although you don't have to hit ALL of these in EACH workout.
When you work a muscle or movement using heavy compounds, in general do those first. IE do the squats, THEN the extensions. Do the Stiffs (I prefer to call 'em RDLs), THEN do the ham curls.
You might consider doing the RDLs earlier in your workout, since you find them harder. That way you the most energy for them, instead of doing them at the end when you're tired.
Also, I'm going to suggest you drop your rep range down for the heavy compounds. How about working in the 5-8 rep range? If you can do all sets in the 8-rep range, increase the weight next time and do 5-rep sets, working your way back up to 8-rep work, then repeat. The reward for going heavier is fewer reps.
