If I were limited to monohulls I would probably choose something like a new Amel 50 or 55. They're very well regarded boats in terms of build quality and design choices. Everything is laid out in a way that makes it (relatively) easily serviceable and materials are chosen more for their hard-wearing properties than their luxury appeal. At least that was my impression of the two older Amel designs I've been aboard. Either that or they had VERY fastidious owners. Amels make a lot of sense for a single handed sailor. Again, the helm position is very well protected and out of the weather, reducing fatigue. It also has tall, all-metal lifelines (the "fence" that goes around the boat) which is great if you need to go forward for whatever reason. You shouldn't, though, since all sail handling is done from the cockpit in an Amel. Most of them (the 50 included, I believe) feature things like big engine rooms for easy serviceability and watertight compartments to improve odds of survival should an accident of some kind occur. http://www.yachtworld.com/boats/2018/Amel-50-3150090/Sydney/Australiahttp://www.yachtworld.com/boats/2016/Amel-55-3071179/GOCEK/Turkey
There are other very high-quality yachts out there. Hallberg-Rassy, Oyster, Swan, Contest and Discovery spring to mind. The few I've been aboard have seemed more luxury-oriented and less "serviceable" oriented, which is extremely important when you're out cruising. Many of them have sail handling focused around the mast base as opposed to the cockpit. Nonetheless, they're fantastic boats with "over-dimensioned" everything (rigs, hulls, keels, rudders, engines, electrics etc) which leads to very rugged and long-lasting vessels that will ride out storms and survive groundings to a much better degree than cheaper vessels will.