They are both procedurals where the guilty party is a character introduced about 8 minutes in without being a suspect and their motive suddenly appears with 8 minutes left in the show.

I prefer Elementary (and am literally rewatching it right now), but that is for how the case unfolds. It has a lot of detective work and drudgery discussed (they don't show hours of looking through files but they comment on it, they show the effort it takes).

The Mentalist is more of him getting hunches then detective work. It is just less believable.

But the main reason I stopped watching Mentalist was that it stopped being a case of the week and had too many episodes about Red John a serial killer who could do anything and had a cult following and was just a silly plot that dragged out for years.

If you want a case of the week show with logical cases watch Death in Paradise. The cases are often locked room or impossible murders that they have to figure out how they were done and who did it - but the clues and how it happened all work. And Death in Paradise always has them list the suspects and the killer is one of the suspects. It makes sense, it isn't just a surprise reveal.