Personally I don't like Apple because they tie you into everything Apple, Danny. They are a very good design and back in the day a graphic designer would not accept anything else. Another advantage is that anything Apple seems to work with anything else Apple with no fuss. Originally they used Motorola processors so they were completely different from a PC but they changed their design several years ago to using Intel processors so the only real difference between an Apple and a PC is the operating system. Physically they are the same so, for equivalent components, they are not very different in performance. Typically I have always found an Apple with the same performance as a PC will cost a little bit more than the PC. Some people like Apple and accept that small price penalty to get their choice. I make no criticism of that choice but it is not one I would make.
Yes, with a PC, typically if you pay more you get more performance BUT it is very much not linear. If you start with the cheapest you get a big increase in performance for a relatively small increase in price but eventually you reach a point where you need to pay a massive increase in price for a small increase in performance.
The problem with the branded PCs that you buy off the shelf, like Dell, Lenovo (used to be IBM) or HP, is that they tend to have a limited number of options. You can configure them a little in the ordering process but there are not many choices. Building one, or having it built, gives you a very wide choice. Usually if you get one built by a local shop they will give you support including sorting any software problems. If you do buy an off the shelf model from a Greek shop make sure the supplier configures everything into English for you. Don't be palmed of with, "Oh it's OK, everything can be changed to English."
A PC is very complicated at detail design level but pretty simple at build level.
1 You start with a box, referred to as a case, to house everything. They are all made to a limited number of standard dimensions.
2 The case may come with a power supply built into it but if not you have to fit one. The power supply takes in mains AC power and converts it to a number of DC voltages each with a suitably rated current to power the components that you connect to it. Power supplies also come in a standard physical size BUT a range of power ratings so you need one powerful enough to drive everything you intend to connect.
3 You then mount a large printed circuit board called a mother board into the box. Obviously the size of the motherboard has to be suitable for the size of the case. They come in sizes such as ATX, Mini ATX, Micro ATX. The smaller the mother board the smaller the case needed BUT the fewer features it will have. I tend to go for a full ATX motherboard and a Midi Tower full ATX case. Everything else connects to this motherboard. You connect appropriate cables from the power supply to the motherboard.
4 There is a special socket on the motherboard to take the processor. This is the bit that does all the work. Intel changes the physical design of the processor from time to time when they issue a new range so the socket has to be compatible with the processor. The current one and the previous one both use an LGA 1151 socket. If everything works out the next range of Intel processors will use a smaller die size so I suspect that will result in a different socket.
5 There are a lot of support chips, referred to as the chipset, on the mother board and they have to be compatible with the processor. The current processor uses a Z270 chipset while the previous one used Z170. There is some interchangeability but using an unmatched processor and chipset usually results in some features not being available. You cannot change the chipset. It is essential to buy a motherboard with the correct chipset for the processor. There may be some alternatives available, such as H270, but they usually lack some features.
6 The processor simply clips into the socket, usually with a lever, and a fan assisted heat sink clips on top of the processor, either with its own heat sink paste or added heat sink paste to ensure good thermal contact. A cable will connect from the fan to the motherboard.
7 Memory chips to store data while the PC is running come built onto modules that you plug into sockets on the motherboard. Often they come in pairs, called dual channel memory, which has faster access time. There is also now quad channel memory where you need 4 modules that is even faster if the motherboard supports it. The modules tend to have a minimum size of 4 GB so if you want to take advantage of dual channel performance you have to fit at least 8 GB and to get quad channel performance you need to fit at least 16 GB, which is not cheap.
8 The memory loses all data when the PC is switched off so you also need at least one hard drive that stores data on rotating magnetic disks. About the smallest hard drive you can buy today is 500 GB but it is virtually identical in price to an equivalent 1 TB drive so there doesn't seem much point. A 2 TB drive is about 57 % more than a 1 TB so good value for money BUT only if you need the extra storage. If you want to go really big 10 TB is about the biggest you can buy today. Drives come in two sizes 3.5" and 2.5". The former are usually used in desktop PCs while the latter are mostly used in laptops, although you can get an adapter to fit them into a desktop PC. The disk drive is mounted in a cage inside the case and connects to the power supply and to a socket on the motherboard. Virtually everything today uses a high speed serial interface, called SATA 6 Gbps or SATA3, so there shouldn't be any compatibility problems.
9 An SSD is an alternative to a hard drive that has no moving parts. It uses flash memory chips which are a bit like the memory modules used on the motherboard but they don't lose data when turned off. They can be accessed faster than a hard drive but are still limited by the speed of the interface. They are much more expensive than hard drives so it is common to fit a small SSD, for the operating system and the programmes that need to load quickly and a hard drive for the files, like photos, word documents etc where speed is not so critical. An SSD would also mount in a cage inside the case and connect in exactly the same way as the hard drive. They are usually 2.5" so may need a mounting adapter.
10 There is another form of SSD that fits directly into a socket on the motherboard called an M.2 interface. Not all motherboards have it and it is quite expensive for a small performance gain.
11 Usually the motherboard will already have a video interface built into it that you can connect your monitor to. If you intend to continue to use your current monitor make sure it is compatible. These video interfaces are not as powerful as a separate graphics card but may be adequate. If not, you can buy from a huge range of video boards, about £25 up to £1,000* and they all plug into a PCI-Express socket on the motherboard and attach to the rear of the case.
12 Finally comes the really tedious part, installing all the software.
Hope that helps people understand what is involved in putting together a PC even if they never do it themselves.
* It is also possible to fit two such boards for even better performance.