I have paid accounts for SemRush and Sistrix. If you need free, but not as up-to-date, use k-meta.com (I have no affiliation with them and they might or might not slap a paywall in front of it once they're big enough.).
Try simple keyword tool with their new features Bulk Analyze for quickly determine the list of your competitors and get the maximum of information in the shortest possible time, or more detail compare - Confront Domains for better keyword selection.