I personally haven't used either however one one my customers who has his own marionette puppet theatre does use Google Adwords and absolutely swears by it (but not in front of the kids:slap). He reckons a good percentage of his bookings and enquiries are due to Google Adwords. Also the financial costs are easily controlled. Hope this helps?
I couldn't get on with Adwords. No matter how I changed the key words and phrases i was spending loads on 'clicks' but getting no work in return. I binned using it over a year ago. Actually i haven't done any advertising at all (apart from having a listing in yell.com and yellow pages) in 15 months and still can't keep up with demand.