You would better stick with one the launchpoint solutions in order to keep the benefits from the Marketo integration.
I got some very good feedback from on24. But it is more expensive than GtW.
What features would be better? You should go through that internal RFP process and think about the customer experience, then decide on 2 or 3 to try.
Are you sure that polls are really welcome? Webinars as a whole are less exciting than they were 5 years ago.