depends on your shop
For a home shop, without question... router in a table with a lift. I have 3 of them.
For a production shop making lots of cabinets with thicker material, doors, moldings,.... 3 HP shaper or larger.
I have a small 1 HP shaper, an old Craftsman, rarely used.
I set it up "permanently" with a glue joint cutter. If I were joining a lot of 3/4" boards, I'd use it way more.
The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)