A mini milling machine can be a useful tool for hobbyists or professionals who are machining small parts infrequently. Choosing the best one starts with determining how you are likely to use the machine on a regular basis, what materials you will be milling, and where you will be storing the machine. Most mini milling machine models are benchtop designs, which means they will sit on top of a workbench when in use. Take note of the weight of the machine before purchasing, as it is likely you will be moving it from one location to another when not in use.
Take note of the specifications of the mini milling machine. This will dictate not only how large of a piece you will be able to mill, but also how deep you will be able to drill during the milling process. If your needs exceed the specifications of the mini milling machine, or you suspect you may exceed such specifications in the future, you may want to consider a larger unit instead, even if it is more expensive and takes up more space. Mini mills are only useful for small jobs in most cases, so users who will use the machine frequently for a wider variety of jobs may not find the mini milling machine to be suited to them.
Try to find a mini milling machine with added accessories that will make the milling process easier. Some machines, for example, feature variable speed systems that allow you to control how fast the cutting bit rotates. This is especially useful if you will be milling a variety of different materials rather than just one. High speeds are useful for metals and some woods, but other types of woods may burn from speeds that are too high. Plastics can also melt when cut with a mill that is moving too quickly.
Consider buying a mini milling machine from a well known and reputable manufacturer. This may end up costing you more money up front, but there is also a better chance that a warranty will be included with the purchase. There is also a greater possibility that you will be able to get replacement parts in the future should the machine break down, and you may also be able to purchase additional accessories after the purchase. Buying an off-brand is not always necessarily a bad decision, but you will run the risk of not being able to get replacement parts.