For starters, whilst the HF-G30 has features more on a par with the Panasonic, it is substantially more expensive, so on pure price terms you’d have to compare the HF-G25 with the x920. Then, in terms of “bang for the buck”, the x920 vastly outstrips the HF-G25. Of course, the x920 only has a single physical manual control (the ring) though this can be toggled between certain functions with the small button right next to it. The Canon HF-G25 has an additional manual control of the thumbwheel at the back. Both then make extensive use of touchscreen menus to amend the settings.
So given its price and huge feature set, the x920 would be my recommendation, especially if it’s your first such camcorder. It’s got so many more features than the HF-G25 (50p, WiFi, auto tilt correction and much more) yet still permits reasonable manual control (focus, exposure, white balance, audio etc albeit some from the touchscreen) and will make an ideal introduction to a “less automatic” way of filming.
The Panasonic has a histogram display to aid with exposure (granted, the G25 has its WFM but it’s so well hidden in the menus that it’s only useable in the most relaxed scenarios where time is not an issue, such as sit-down interviews). I think the Panasonic tends to have a somewhat oversaturated look by default though, so beware of this; you may need to tweak its settings either in camera or during your edit.
Panasonic tend to update their consumer camcorder line (which is how they class the x920) every year, so you’re always going to live with that problem. The fact is that’s it’s a very decent camcorder at a very decent price (I found it for £720 inc VAT & delivery at a Panasonic dealer in Sheffield) and if it fits your needs now, then why not buy it!