Any one of those systems will do you well and last for 5 years (probably longer). Also, there really won't be a need to upgrade any of those machines considering your needs.
Your neeeds don't seem to be too intense, so I would rule out the Mac Pro. No need to spend money on a professional-level machine if you aren't doing any daily, professional-level work with it. :black:

So, it really comes down to if you want an all-in-one design or not. There is nothing wrong with getting an AIO. A Mini with a nice LCD is going to cost pretty close to an iMac, so there really isn't an issue with cost here.
Just go with whatever design fits your space and personal style best.