Yes I was so confused to when I bought mine. I have had mine on for awhile now, and now there are even more companys. I did lots of research about the three different types of panels available. I ended up buying from Solar Shop, now would I go with them again, not sure. Prices have come down so much, I could have double the panels I have now at todays prices
My advice is, go for the largest system you can afford. I am a large electricity user and knew my system would only supplement mine, but I am still happy. If you intend upgrading your panels later then go for a bigger inverter. Go with the good inverters not some cheap rubbish, having said that not sure what is considered the better one's these days. Go for a company that gurantees thier panels for 25 years.
I think it is a controversial thing solar panels, my father has friends who think they are the biggest load of rubbish, I think they thought they would cover all of thier costs, it does depend on your size system and your usage. I love mine and would have them again.
Beware of the fly by nighters.
Let us know who you decide on.