I have also researched a few tools myself and would like to share what I have found so far.

Urban Turtle pros – product backlog tree view, integration with TFS, includes both methodologies. Cons – busy interface, lack of visual appeal and ease of use, no time tracking and file attaching, lack of flexibility. Pricing $8-6 per user/per month for a yearly subscription, depending on the number of users.

Eylean Board pros – easy to use, visual, flexible, integration with TFS, MS Project, Outlook, fast to learn. Most beautiful design. Cons – runs only on Windows. Pricing: free for personal use, $12.49 per user/per month for team edition.

LeanKit pros – available on various devices and platforms, user-friendly interface, mobility, cons – covers a narrow spectrum of functionalities, only suitable for Kanban practices. Pricing free for up to 10 users, $15 or $19 per user/per month depending on package.

Scrumwise pros – easy to use interface, includes various functionality, cons – lacks reports, lacks flexibility towards user preferences (for example -backlog placement cannot be changed). Pricing $9 per user/per month.

Kanbanize pros – clean interface, easy to use, multiple platforms, cons – does not include scrum, lacks certain functionality. Pricing from $9 for 5 users/per month to $249 for 100 users/per month.