One idea behind rack mounting is compatibility. There's basically two standard sizes, 19" is the most common for computer equipment. 21" is typically only used in commercial telecom installations (like inside a phone company central office). Depths vary. So pretty much any 19" rack is going to be the same as any other, in terms of whether stuff will fit in it (by width). The differences between racks is the mounting holes. Some use threaded holes. Some use unthreaded round holes (designed fr using cage nuts that clip on). Others (sometimes Dell and APC) use square holes designed for a different kind of cage nut that pops into the square hole. An advantage to cage nuts is you don't have to worry about the holes becoming cross-threaded or stripped out.
Swing-out racks are useful in some situations. They're generally not going to hold as much weight as an upright or fixed place would. Swinging out a lot of equipment and wiring is not as trivial as just opening a door or an access panel. You're putting the wiring at risk by moving it a lot. So generally I wouldn't use a swing-out without having all the wires come to wall plates of a patch panel on the wall. That way you'd only be moving easier to replace patch cords.
Also note swing-outs like that one require side spacing for the equipment to pivot. You're not going to use that one for a flush-mounted panel. For flush mount you have to use a slide-out and then pivot kind of setup (or just slide-out).