I have had Viking, Bernina and now a Brother embroidery machine and the Brother is the one that has given me least headaches! Handles all threads - no hizzy fits. Personally I think a 4x4 machine to start out with is just right. Some find that embroidery is not for them so a smaller machine is less cost and could be easier to sell on to somebody else who wants to try. Don't forget that the smaller the hoop the easier it is to hoop and get good results. Larger designs in larger hoops make for trickier hooping and bigger risk of misaligned designs.
Personally I made do with 4x4 for 13 years before going on to 5x7 for another 6 and have only recently moved up one more notch to a 7x12. I love ME but I doubt I will go larger because I do find it difficult to hoop well enough for the 7x12
Have fun when you get the machine.