ClickFunnels is a hosted platform - this means they own all your content, and can add any of their own tracking or pixels to your pages - plus they have full access to all your website data.
With OptimizePress, you control your data - and maintain ful ownership over your content and website. OptimizeFunnels runs on WordPress, which gives you a huge degree of flexibility and customization for all your funnel pages - you can even integrate with external tools for additional functionality where you need it.
ClickFunnels cheapest plan costs $97/month ($1164/year) vs OptimizeSuite which is currently priced at only $199year! So you're saving almost $1000/year - and that's assuming you don't pick their $297/month plan!
So - maintain more control over your websites and funnels, and choose OptimizePress.