Saddles are very much a personal preference. The monoflap style are designed for fast work, show jumping and cross country, so have the blocks and tend to balance with a shorter stirrup length, which works well for some people. Research suggests monoflaps can assist rider stability. The long billets make it easy to fit a short girth rather than fiddling with different girths as you horse grows and shrinks with diet and exercise. Durabilty reports are variable. Most monflaps have foam not wool flocking: opinions differ. The cost is usually higher because they are soooo trendy and, like, modern (with
big advertising budgets). The conventional saddle has the sweat flap and are generally more robust because of the heavier leathers used. They were initally designed for foxhunting in particular and a sweat flap is useful for hours of hard work. The stirrup length is perhaps more adjustable, useful if foxhunting or trail riding when taking a hole up or down eases tired legs. The shorter billets put the girth buckle under ones leg: depending on the saddle, this may or may not be a problem for you.
You may find a conventional saddle more adaptable for the different activities you wish to do but some people swear they will take their monoflap with them into their grave.