I use Lexol cleaner and really like it. I also like a good old fashioned glycerine bar or liquid or gel Murphy's Oil Soap. Castile Soap (in the laundry isle or "organic" isle) also works well and is a mild cleaner. Using plenty of water is key to lifting out dirt and getting leather really clean. I use an old soft bristled tool brush to get in to cracks and around/under hardware.
After cleaning, follow up with a good conditioner. For light conditioning, between heavy conditionings, I like Belvoir spray Conditioner (do not like their cleaner, it has alcohol in it!) or Hydrophane conditioner. For deep conditioning, I like Passier Lederbalsam or Bienenwaches Leather Balsam.
If you keep up on cleaning your tack, wiping it down after each ride with a damp cloth, cleaning before a show won't be such a chore.