Upgrading My Camera Lumix G10?

I have the Lumix G10 and i bought it when it first came out for around £600. Its a great camera and i've have some really good shots with it, but there's one problem with the camera that really annoys me. And thats the Add-ons.well, what there's of them. There's only 2 lenses that fit this camera including the default one your get. I want a camera that i can get lots of lenses and extras that arent going to cost a bomb, i was thinking like a Nikon, or a Canon? But i don't know much about them and what ones are the best at the minute? I don't know how much my camera is worth now and i want to spend around £600 on the camera and what ever else it costs for a lens. Please would you be able to help me with prices and best cameras for my price range.

Canon eos 600d or 650d amazing camera! Most youtubers use it to record their videos you can also buy lenses for it its honistly amazing and you won't regret buying it i got mine with a small lense at about 500 but if you want you can buy boom bars and light that attach its a pro camera, hope this helped good luck buying!
:)

It takes lenses in the micro four-thirds mount - Olympus and Sigma both make lenses to fit.

As I understand, the G10 is micro four-thirds. You can use any four-thirds mount lens from any brand so you are not limited to just the two lenses Lumix makes.

Of course the lenses will cost more if they are better especially if you get from Leica. It's worse with dSLR's and other mirrorless formats. You will be forced to just get from the same brand and system.