Welcome to the board. What a big and wonderful decision. We usually suggest people wait to buy until testing out various models and suggests expos as a good place to try the various brands out. Except for this year... Still it helps to sit down at one of them and see if you and the machine can work together, different people just think differently and sometimes one brand is better for them than another. But all brands have their fans and for good reasons.
For table top models I always suggest as much throat space you can afford. It still always helps with bulk, but don't think that matters quite as much if you will be using a frame. Sure, it always helps but what I found is that I still can't easily quilt a design more than about 10" wide because of the length of my arms. Another friend's machine she has on her frame is smaller than any of those you are looking at (think it is just 10" throat), and she has found she can not back quilts with minkee because of the amount taken up on the roller bars and her relatively small throat.
I'm sure all of those machines have bobbins that are L or 15 or maybe M which are all standard sizes. I've found I really like buying prewound bobbins from my longarm experience which is now moving over to sewing bobbins as well. My Bernina has a proprietary bobbin that is extra large but is also extra expensive, you can't buy in stores, and you can't buy prewound bobbins. Not all that big an issue, but if I had the embroidery unit (and used it!) it would probably annoy me pretty fast that I couldn't just buy a big box of bobbins ready to go. The machine I used was an M bobbin, which is not common around here, I could buy prewound but just had to order it directly.