I personally used also ProWritingAid, Sapling, WhiteSmoke, and Hemingway and they are all pretty good, with even some more advanced options than Grammarly has.
I want to know why you are moving from Grammarly to other alternatives. From my side, Grammarly is a great tool. If you are a writer then it will most helpful to you in grammatical mistakes, if you are using a paid tool then it supports more punctual tool, you can check plagiarism of any articles from Grammarly premium, it can benefits you.
ProWritingAid offers similar grammar and style checks, while Hemingway Editor helps with clarity and conciseness. Consider WordTune for sentence rephrasing or Readable for readability scores.
ProWritingAid gives you a solid grammar check and dives deep into your writing, plus it’s usually cheaper than Grammarly. They even throw in student discounts, which is pretty sweet. QuillBot’s got a free version for basic grammar checks and paraphrasing, and if you want the full deal, their premium plan won’t break the bank. Hemingway Editor is great if you're trying to keep things short and sweet (perfect for research papers) and it’s a one-time payment for the desktop version, so no ongoing fees. Oh, and don’t sleep on LanguageTool. It’s free for the basics, and their premium plan won’t cost you much.
Given your need for aceing research papers, I'd highly recommend looking into ProWritingAid, Trinka AI, and Paperpal first, as they are often geared towards academic writing and offer more in-depth analysis than basic checkers. Then, consider LanguageTool and QuillBot for their strong free tiers and competitive premium options.