If you want a tool to preview how your site will look on Google's search results page, SEO Minion is worth a look. This browser extension for Chrome, Firefox and Edge can analyze and optimize on-page SEO with a more detailed SERP preview tool. It can show you how your site will rank for a given set of keywords and even simulate multi-location SERP rankings, so it's a good all-around SEO tool.
Another good option is Moz, a collection of SEO tools to help you improve your online presence. It's got a lot of features for keyword research, competitive analysis and rank tracking, but its STAT tool is good for monitoring and analyzing SERPs, too. Moz also offers a 30-day free trial so you can try it out.
If you want a more general-purpose SEO tool, Ahrefs has a range of tools, including Site Explorer for analyzing website backlinks and traffic, Keywords Explorer for finding the best keywords, and Rank Tracker for monitoring keyword placement. Ahrefs comes in several subscription levels, so it's good for people at different levels of expertise.
Last, GetGenie is an AI assistant for WordPress users that's designed to help you create content faster and optimize it for search. It uses SERP analysis and AI to generate content that ranks well, and it's got tools like SEO research, competitor analysis and SERP visualization. It could be good for people who have to manage lots of sites and want to free up time for SEO chores.