When you finally buy a computer, a better or cheaper one is bound to appear the very next day. That is because we are in a fast-growing industry. It is easier for me to tell you what not to get. Don't even think about buying with a view toward upgrading your new purchase later. It does not happen.
New standards appear continuously, obsoleting older computers.
Even items as common as memory modules keep changing. If you have no plans for special hardware additions, then one of the brand name machines selling at a rock-bottom price cannot be beat. That makes it difficult to add hardware later. In those cases it is best to make sure that you get a long warranty. The monitor is an exception, and can easily be kept.