If you look at a 10" and 12" side by side in a store, you'll realise why so many here are saying you should go 10", particularly for what sounds like your first scope. A 6 or 8 inch scope used to be considered a wonderful instrument only 10-20 years ago. While you're learning things be conservative - there will be times you may well put off observing if its cold, dark, wet and you have to lug the 12" about.
As to the 6" Meade, do you want the scope to show you brighter objects easily and point to where the faint ones are OR do you want to learn how to find everything by charts and finder and actually see something when you get there....
(mind you, you'll probably find less objects in a night with the dob of course)