Finasteride (and dutasteride) blocks DHT conversion.

Spiro blocks T production, but as a side effect - its primary use is as a potassium sparing diuretic blood thinner. As has also been said, its also a weak estrogen antagonist.

Cyproterone Acetate is a progestin that also blocks gonadal T production, but thats all it does. Since its progestonic it will bind to androgen receptors and can have a few side effects from that.

Bicalutamide binds and blocks androgen receptors making your body not respond to T, but doesn't actively stop T production in and of itself. However high amounts of free T from it never binding will eventually raise shbg and eventually slow the pituitary gland from signaling to make more T.

The one you didn't mention was lupron / gnrh agonists, that hyper stimulate the pituitary gland with gnrh until it becomes resistant to it, at which point it stops releasing LH and FSH and the gonads stop producing T. This has no side effects ever but also does not interfere with adrenal testosterone production, just gonadal.