The FTb is a really good camera but the CdS meter is slow in response (in low light) compared to the AE-1/ AE-1P / A-1, which meter instantly. With the FTb, on low light, you need to wait for the meter needle to settle.
As for reliability, the Canon A-series camera are reliable, to be honest. The shutter on them is very very reliable. It was so good from the start, that the same shutter (introduced 1976 on the AE-1) was used unchanged on the AE-P (1981). As for the electronics, the AE-1P is much improved over the AE-1 for many reasons, one of them being better, more streamlined circuits.
Now, for the problem the OP is experiencing on his AE-1: The AE-1 uses a string&pulley arrangement to relay the ISO setting and shutter speeds to the variable resistor of the camera. They are located at opposite sides of the camera. If this string breaks or gets stuck, the problem will be similar to what the OP is experiencing. Fortunately, it is an easy repair.
The AE-1P does not require this string, as far as I know, making for a more reliable camera.
In any case, if the OP is looking for a manual match-needle Canon camera, there's no substitute for the Canon F-1 !