I'll be the odd gal out as I love my glass cooktop and find it far easier to clean than the old solid burners that I had. I do think it may have to do with the age, as I know some of the earlier glass tops did scratch, etc easily. I just wipe my down everynite after dinner and a few times a week I use a glass cleaning wipe. You do need to be careful if you are cooking with sugar as it can leave permanent marks on the cooktop if it boils over.
The reason I prefer the glass to gas is that I have lots of allergies and gas is not recommended in homes with children or adults that have allergies (or chemical sensitivities), especially asthma. You'll find the medical research actually has mixed views, BUT I tend to err on the side of caution and the reports indicate the importance of proper ventilation when cooking, so you might want to consider upgrading your ventilation (and make sure it vents outside) if you're installing a gas cooktop.
I totally agree with all the others that in terms of cooking and controlling heat, you can't beat the gas.