I'm on my second Pioneer AVH model. The only reason I switched from the 2012 AVH-P4400BH to the 2016 AVH-X5800BT is for XM. You can buy a SiriusXm tuner (SXV300) that will plug right into the back of the head unit. The radio also has spotify and Pandora on it that will integrate with your phone on the screen via Bluetooth or usb. Also, if you can get it to work, they have AppRadio which will display your screen on the radio face. I say that because it doesn't work with my Samsung s7 edge. Iphone may work better. In my experience Pioneer is the cheapest option for a double DIN radio and I have never had a problem.
As for the XM antenna, I removed my onstar antenna by dropping the headliner, which gave me access to the bolt holding the antenna in place. I disconnected the two coaxial lines from the antenna and hooked up the blue coax to a buick rainier xm antenna I found on ebay ($20). That xm antenna will go right in the hole in the roof the onstar antenna left behind. The xm lead from the buick antenna is the orangy brown one. You can then find the other end of the blue coaxial wire under the passenger side dash by simply dropping the glove box out of the way. It is plugged into the onstar module under there. Unplug it and remove the blue outer plastic shell then plug it into the Siriusxm tuner. It was a good solution to make the roof still appear factory and not use the magnetic xm antenna that comes with the SXV300.