I was wondering, which series/ Cherry would i get, if I were to order a mechanical keyboard that is most like my Unicomp 104, I want the most clicky feel noise be damned
Nothing would really come close sadly, the only thing you could possibly compare it to would be Cherry MX Green which are medium spring rate and tactile+clicky. But, currently there are not many boards out yet that have full Green switches; there will be soon-ish, but not sure how long you're willing to wait for decently priced mass-produced versions.
You would want blue or greens. The main problem is the audio queues will be different. Depending on how you type if you normally bottom out keys they will make two sounds(click clack) while ibm keyboards tended to make only one.
Be warned that their will be a transition period. Cherry keyboards have always had linear key placement. While oldschool keyboards like the ibm model M and unicomps place the keys on a curve to reduce effort required to hit keys on non home rows. So if you are expecting to work in a production environment while switching keyboards consider staying with an oldschool keyboard.
Basically buy another unicomp or at least keep it as a backup. If you still require a cherry based keyboard make sure you get one with a built in wrist rest or buy one separately. This will help to reduce miss hit keys and fatigue slightly.