It all depends what your budget is and what sort of a desktop you need? If you want an all in one high range then they can vary from the new Apple iMac Pro which can cost up $20,500 (which is a ridiculous price) to one of the more reasonable ones (for its price) which is the 'HP ENVY Curved All-in-One - 34-b011a, it comes with an Intel® Core™ i7-7700T 8-16GB ram with an AMD Radon RX460 graphics card and is a great unit for around $3,699 that's in Australian dollars, if you want an average all in one then HP, Dell and AUSUS make some good ones from around $1500 to $2500. If you want to build your own then I would again ask 'what price do you want to pay' as you can build some good units for the same as an 'All in One' or even better for the same price. My long standing preference in mobos has always been ASUS (I'm going back 18 years with them) they are well designed, reliable and perform very well, as far as a cpu the Intel i7's and i5's are very reliable and handle multitasking very well. As far as storage is concerned, you have to have an SSD or an M2 (Samsung are a proven performer in these formats) as their speeds are far superior to the old spinning platter type HDD which have been around since the 1950's. For ram, the DD4 is the current and speeds vary as do prices, Corsair, Crucial, Kingston G.Skill’s all produce some excellent ram but, the faster it is the more expensive it is, you have to choose what your budget dictates. For gaming I would go to an AMD Ryzen cpu and AMD Radon gpu, gamers prefer these as they can be overclocked and have been proven. As far as graphics cards (again choices are limitless) but, if you want to run Windows 10, I would select a GeForce card as they are more reliable with drivers and Windows. As far as monitors are concerned, your choices are limitless, the new 'All in One' desktops have touchscreens but, the desktops that you build you will have to purchase a specific touchscreen monitor for it to perform that function e.g. a 22 inch 'Multi-touch Monitor with LED' will retail for about $380 AUD. I've built many computers and I'm in the process of building a $6000 desktop which contains some of the components that I've mentioned above. Your choices are limitless when you build your own.