Here at EmergingEdTech, we're big fans of the work our friends at AppED Review have done over the years. AppED Review started reviewing smartphone and web apps using this Comprehensive Evaluation Rubric for Assessing Instructional Apps back in 2012. They've reviewed hundreds of smartphone apps, and later added web apps to their process.
Stop by and check out their reviews of apps that you might be considering, and explore their site to find highly rated apps for your classroom!
*Disclaimer: I am also on their Board of Advisors (an unpaid position). I have not received any compensation for this or any other post or page about AppED Review (I just genuinely respect the product and service).