^ same here with 7 different after market ones, have not tried a dealer one yet. Your best off to get a rebuild kit for the master cyl, really you cant use the whole kit because one of the seals is just cut wrong, same reason new ones dont work. I went to the junk yard pulled one off a supra, and used the reman one I got to rebuild mine, mainly just replacing the rear piston seal. I really need to do a write up on this, but have run out of used and reman ones.
As for the hissing that is going to be a bad booster most likely. What happens a lot of times is when normally use your brakes there is only a small amount of travel on the booster. But when you are bleeding the brakes or have not fluid in them what ever, your brake pedal will travel further pushing the booster past its normal point and can make it leak. As for the master if you had no fluid in it and then added some and bled it out you might have torn a seal, if it sits dry for a while then pushes past the dry area while you try to bleed it it can rip the seal, I have seen this many times.
As for the master, the conditions you get are as described, normally if you press the brake hard and fast you will have good pedal, but if you press it slower it will just leak down, until it gets near the floor then the front piston in pushing on the front brakes and the pedal stops moving just before it hits the floor. I had to drive my car home like this and it was not fun with only the front brakes working.
It is really easy to take the master apart and inspect the seals just need a 10mm wrench and a pair of snap ring pliers. Take the 10mm bolt out of the front of the master (not on the front but near the front on either side or bottom). This bolt holds the front piston in place so it cant travel to far back down the chamber. Press the piston in some with a screw driver and remove the snap ring. The piston will come out now, there will be a piston on the rear with the seal on the very front of it being the bad one you need to look at. If you want you can then pull the front piston out as well and inspect it.
I used to be able to get master cyl rebuild kits from napa but I dont know if they still carry them because its getting harder to get any kind of rebuild kits from them.
Btw older cars have steel or cast ones, dont know which but they are black, new ones are aluminum.
Here this should help.
http://store.driftmotion.com/static/i-brakemastermk3supranoabs.php
http://store.driftmotion.com/static/i-brakemastercylinderrebuildkit90-92mk3wabs.php
http://store.driftmotion.com/static/i-brakemastercylinderrebuildkit865to90mk3wabs.php
btw if you are going to rebuild it you need to check the bore inside the master for pitting or scratches, and you will want to hone it, you can use a wheel cylinder hone, they are usually around $5 or so.
