XA-10: Actually there is a hotshoe without the handle
When you remove the xlr handle, there is still an industry standard hotshoe. That's something the HF-G10 does not have; the G10 only has a Canon proprietary hotshoe. I found that quite limiting on the HF100 I owned; even though you can buy an adapter, the hotshoe is small and not robust. The small LED attachment light I used pulled the tiny screws right out.
The hotshoe on the XA-10 is very sturdy and can even handle a bracket with light and mic.
The main differences between the two cameras are these: 64gb of internal memory vs. 32gb, the infrared feature and emitter, the tally light, and, most importantly, the xlr inputs with individually controllable input levels and 48 volt phantom power This is important if you're into pro-level sound quality. Most really good pro mics need balanced xlr inputs. You can buy an adapter, but the good ones (like the Juicedlink 454) are about $400 and aren't nearly as handy and compact as the X-10's xlr handle.
Also, the X-10 with handle and shotgun mic attached looks much more professional. As shallow as that is, It's important in some situations (like weddings) where you need to differentiate yourself from others with iPhones and small camcorders.