It does depend how hilly your area is, mid drive will be a lot better at tackling hills when compared to a hub drive motor so I think you should factor this into your decision.

When I built mine (10 years ago) mid drive was considerably more expensive as well although I'm not sure on the prices now, I presume it is still similar as hub motors are generally just cheaper tech. Mid drive will also come with additional costs in the form of wear and tear, it puts considerable amounts force through your drive chain which will wear out chains, cassettes etc a lot fast so you will be needing to replace them as general maintainance when they start to wear out, you also need to bear in mind you may snap chains due to the additional torque going through them.

Hub motors are going to be cheaper to maintain as well as install. Essentially you are just adding the wheel with the motor on, running the cabling to your controller, battery etc and away you go.

You should add some form of torque bracing with those little arm things, you can get a battery that attaches to your bottle cage mounts but it is a pretty simple install.

I personally think you should go rear hub and it keeps the weight over the back of the bike, it drives the correct wheel so you weight keeps it from just spinning out but also I have heard of motors twisting forks from the added torque where as I've never heard of one twisting a frame in the back.

The easiest will 100% be a front hub motor but then all that weight is over the front of the bike and it just seems wrong to me personally to drive a front wheel but you need to weigh up the factors and decide what is best for you :)