Mountain Hardwear - Bozeman 15

https://www.mountainhardwear.com/p/lamina--20f%2F-29c-2095141.html We use this model and the Bozeman model from Mountain Hardwear on Kilimanjaro, and they work really well, with only minor issues with the zippers (not very durable). If you are looking for a warm sleeping bag, this is a good choice, but it is quite bulky.

My 11 year old 15 degree Mountain Hardware Synthetic mummy is as reliable as it gets, I've used it down to 22 degrees with a windchill in the teens and was comfortable. I trust it with my life. It's not even that heavy, right at 3lbs... only problem is that it's bulky. 12L stuff sack. I went with down for my hammock quilts, but if I have to sleep on the ground and worry about water intrusion or tent condensation, I'm using the MHW.

Mountain Hardware has a couple bags that are compatible, my wife and I use them. They are a little bulkier, but affordable. You could also look at something like the Zenbivy Double bed.

I have the Mountain Hardwear and love it. My kid has a North Face Inferno and loves it… and I worry less about water damage. I trust OutdoorGearLab.com for reviews. 

It's really a personal choice. I would suggest you try the MH sleeping bag. It's a free way to test a type of sleeping bag. Worst case, you buy another one later. I personally use down sleeping bags because they are lighter and compress better. But they are more expensive and take a lot longer to dry if it gets wet.