Both Brother and Janome are good machines. You'll get a nice quality stitch from either. I had the smaller Brother machine for quite some time...I gave it to my daughter when I upgraded to a Baby Lock Ellure.
Generally, the $400 Brother machine will sew the same quality stitch as a mid priced machine. The difference is the size of the embroidery field. The $400 Brother has a maximum field of 4"X4". Although that sounds small, it's acutally suitable for text. Also, if you're talking about putting logos in the "over-heart" position of a polo, or jacket, the 4"x4" will work since the industry standard for sizing on those designs is 4"x4" or smaller.
The Janome Memory Craft 300 has a larger embroidery field of 5.5" X 7.9". One nice feature of the Janome is that you don't need to attach a seperate unit to do embroidery -- the hoop attaches right to the machine.
On board features for sizing designs, etc. are pretty similar between the two machines.
Both machines would require a card reader/writer, and blank card to transfer designs from your computer to the machine -- neither have a USB port. These are not terribly expensive, and because both machines have on-board fonts for lettering, and a large selection of "built-in" designs, you would not need to purchase additional software, and a card reader until you're darn good an ready.
I have some articles on embroidery machines, and software on my site -- if you care to have a look, go to
SewMimi.com