For my first Trademark, I was recommended to use Trademark Engine. That was a big mistake. The site doesn't do any extra work. YOU essentially are entering the EXACT fields that are required on the actual USPTO website and then they simply copy and paste all the fields on the USPTO website for you. I am NOT kidding - you can literally go and check both sites. You are paying $99 to Trademark Engine for just doing this. Oh and BTW, their nonsense about 'Researching to see if the TM is taken" is literally a 5 second job on the USPTO website. You just need to enter the Trademark term that you want in the search box (TEAS) and see if it has been taken. They make it sound like it is something massive.
Besides this, they actually had the nerve to over-charge me. So they charged their fee and they charged me $275 to file with the USPTO (the USPTO filing fee). It was only later, when the USPTO sent me the email confirmation, did I realize that the actual cost was only $225 - so they happily charged me $50 extra.
These people are scam artists and they refuse to talk to me about this or answer emails. I have filed a dispute now with my card (who told me that they will get the refund soon).
Stay away from this company and file yourself.