All of my appliances match as far as brand go, but most of them came with the house. The fridge did not, I already owned it, and it just happened to be the same brand.
The upside of matching appliances would come when you need repair (unless you use an independent repair person who works on many brands). When I needed a microwave repair, I had the same guy look at my ice and water through the door. He fixed both, and as a side thing, he didn't charge repeated visits, although it took him multiple visits due to parts, etc. When a girlfriend needed her fridge repaired recently (a developer repair messed up her door handles), I suggested that she order filters to be replaced at the same time. Why not?
Next time I get a fridge, however, I will probably get an LG, even though my other appliances are GE Profile. Why? Because I find that LG's fridge design is much more suited to my needs and lifestyle.
So I've told you both sides of the coin. Don't shop just by price, but shop by features as well. Make sure you get the features and styling (usability) you want, because good appliances are things you will live with for many years.
That's my opinion, for what it is worth.
Fern