There are a lot of different options when it comes to an invert. The main thing is to make sure it meets all the Requiremnts to pass your electrical inspection. Most importantly it must meet UL and IEEE codes (check local codes to know what you need).
I used a transformerless inverter, and am very happy I did. It made the instalation very simple, and there was no need for a GFDI. Basically with a transformerless inverter you run all your panels in a series, and then run the lines into the inverter. You just need to make sure the voltage is correct for your inverter, and your inverter can handle the Watts you are producing. Also the other problem I ran into was that my electrical inspector did not know anything about a transformerless inverter, and wanted to make me add the GFDI, and stuff not made for my inverter. It took a few days for him to figure it out, and realize I had done it correctly, but he finally passed it off.