Today in many respects Mac and Windows computers, running recent versions of their respective operating systems, are more alike than different. A lot of the bad mouthing that people who switched from PCs to Macs do (or that Linux advocates refer to) really relates to the state of affairs with Windows 3 years or more ago (and some of it is just myth). These days, if run on decent hardware (there are still really cheap Windows machines with deficient hardware), Windows is as reliable as a Mac and there are few, if any, of the old hassles that required a re-install of Windows periodically or else it bogged down. Both computer types can be equally secure or insecure, depending on what the user understand and does. One type doesn't outperform the other, though there may be specific tasks that a PC does better than a Mac or vice versa. Same with Linux.
The Mac advantage has always been that Apple tightly controlled both the hardware and software side and didn't have to worry about working on thousands of hardware variations. It has always been somewhat of a miracle, IMO, that Windows could work as well as it did considering all the possible configurations of hardware and software it was asked to run. Apple also didn't have to worry in most cases about backward compatibility and could totally change their systems periodically, even if it meant that users of its newest computers would essentially have to start all over again.
The simple fact is you can have a reliable, hassle-free Windows or Mac or Linux computer. The important thing is to get a computer that does what you want it to do and that you can live with for a long time. The questions should be: does it work in a way I am comfortable with? does it run the software I want to run and need to run? if a laptop, does it offer the form factor, weight, screen size, keyboard, etc. that I will be comfortable with?
Whatever computer you have now that you are unhappy with needs one of the following things done to it: repair, replacement with a more up-to-date version, or switch to something else.
There is no best computer. It is what is best for you, your personality, and your needs.