There are already quite a few threads on here regarding various machines and their advantages disadvantages so I won’t go into which mini to buy, but I’ll give an opinion on the excavator v. mini skid question.
An excavator with a rotating grapple is an excellent machine for feeding a chipper. However, it is a lousy machine for dragging brush out of a back yard. It will be just plain slow. A mini skid feeds a chipper quite well with a bit of practice, and is a great machine for pulling debris long distances. If you are buying only one machine, and you are primarily using it for trees, I would recommend the mini skid with a Branch Manager grapple.
As for what machine to buy, I like minis in the 1000 pound operating capacity class. Much smaller is not very productive in my mind. I’m a fan of both Ditch Witch and Vermeer, but there’s others out there as well, and many that are good - a lot of the decision comes to personal preference and dealer support.
We only do trees, so we rarely use a loader for anything other than moving brush or logs. However, in my past (landscaping and excavating) I ran both machines for earthwork and both do well at it, provided you’re using the correct machine for the task at hand. An excavator digs holes well, but doesn’t do finish grading. A mini skid will finish grade nicely, but good luck digging footers for a house with one.