I tend to love what I'm used to. I loved my 99K Singer that I sewed on for years; it did nothing but straight stitch but it did that extremely well; over the years I made a ton of clothes on that little machine, from baby clothes and blankets to my own wardrobe. Then my husband bought me a Golden Touch 'n Sew and I loved and sewed on it for years -- and still love it, in spite of its bad publicity, and still sew on it. Then my husband (yes, he's one of those "let's surprise her" guys) bought me a Brother 450Q. Completely different from the Singers so there was a learning curve. But I have to admit I've grown to love the convenience of this machine. The needle up, needle down feature -- I no longer pull the thread out of the needle when I begin to sew which I frequently did with my other machines, even though I've been sewing for donkey's years! -- and the automatic back stitch, all the computerized aides........it's really spoiled me in that respect. But I still am not convinced it makes as nice a stitch as the Singers.
Not sure how you choose without spending money unless you just go to dealers and try everything they have. Frankly, I think I might have bought a Viking, left to my own devices (had I not been "surprised" by my DH) but now I'll never know. So much is decided by personal taste, and budget, and convenience, and habit, I think.
Good luck on finding the perfect one!