If I'm not mistaken the 635 and the 730 both have the 9mm stitch plate giving you almost double the size on your decorative stitching. The 630 features the 5.5mm. The 630 and 635 do both have push button start for regular sewing which is a favorite of mine. My choice would be a 9mm capable machine with the push button start for sewing...which leaves us with the 635. Good Luck!

I love my Bernina machines. I started out many years ago with the 150QE (Quilters Edition) and I still have that machine. Since then I have owned a Deco 500 and 650 which were embroidery only. Traded up to a 165 that would sew and embroider. Sold that one and moved up to a 200 which I later upgraded to be comparable to the 730. A year ago I took the plunge and purchased a floor model 830 from my dealer when they came out the the 830LE. My serger is also a Bernina. A good dealer makes the experience really great due to the training you get.

mltquilt

I just happened upon this and will throw in my 2 cents. I've had a 730 for about 4 years now and really love it. The good - in my lifetime I will never be able to take advantage of everything fully. I've never had a problem with it other than the fact that my bobbin sensor doesn't always tell the truth. I'll mention it again when it goes in shortly. It also comes with the BSR for free-motion (not sure if one or both of the other models you mentioned come with it). I've gotten very fond of that attachment.
You need to consider the 5 mm or 9 mm facets as well, I don't mind the 9mm and use a single stitch plate for straight sewing with no problem. I am an all-around user from garments, upholstery and home dec, quilting a bit more these days. It seems to work well for me.
Good luck, Deirdre