Bundles always seem to sell for less anyway, no matter where you sell. So to get the best prices you have to be prepared to put the effort in and sell separately.
Ebay will generate the best prices, even after you take off fees, because it's the largest market to be selling in.
But there's the risk of dodgy buyers claiming they didn't receive their items if you don't use recorded delivery on everything.
At least with Gumtree you can advertise to a wider market than on the MM here, you deal face to face and it's free to sell.
Carboot sale is an option, but again you maybe won't sell your items if your prices are too high.
Selling to places like Cash Converters or CEX means you will only get a fraction of the market value.
The MM here is an option, but you'll get less money than eBay and most potential buyers will ask you to split your bundles anyway.
I suppose a lot depends on what you actually have and if it's the sort of stuff that sells.
If it was me then I'd start with Gumtree and the MM and see how it went.
It can be slow going to get stuff sold on the MM, but at least in the console section it doesn't move very fast so you don't have to keep dropping prices to stay on the first page.
