Like pat said depends on what you want to do with it man. Also your budget. If your gaming on it you definitely want a high end machine. IDK the market prices as of late but its usually cheaper to custom build if you want a gaming machine.

If you are just using it for the run of the mill functions then it doesn't much matter because all computers have plenty of hard drive space plenty of R.A.M and decent processors these days.

Hewlett Packards have always been good for general usage in my own experience. Never fucked with macs though so they may be better…..

You'll just have to do a little research based on your budget. Most companies offer the option to build custom pc's so that's what you probably want for a gaming machine. All the components are important  but if you are really strapped for cash a good processor and a good video card are absolute necessities for a gaming machine. It just won't be able to keep up with the software otherwise….

Also computer technology moves ahead very quickly so I would go with a desktop so you do have the option to upgrade your hardware if you do so chose. Alot of times you can upgrade laptops but it can be time consuming and/or costly.

Pat might be able to help a little more than I can. I haven't been pc gaming for a long long time. Im on a laptop now and don't have a desktop