Which carriers/service do people recommend to send documents and small packages from UK to USA (FL)?

Looking for reliability as main priority.

USPS, FEDEX ....

UPS and FedEx are much of a muchness.

With RoyalMail - US Postal Service there is a hand-off between the two, which historically has led to a break in the tracking in a few cases, with the sending side saying they handed the letter/ package over, and the receiving side saying they have no record of actually receiving it, so the tracking feature was useless. I hear it is better these days, but I have no personal experience.

UPS and Fedex are a bit of a hassle for me (Offices are 8 to10 miles away) so I usually use my local Post Office/UPS tracking. My daughter had to file a US corrected tax return in January and used the Post Office/USPS and it worked for her. As usual it got to the US in 24 to 48 hours then bounced around various sorting offices in the USA for a few weeks before being delivered but she did get an email each time it was moved in the USA.

I sent my old UK passport via UPS to the HMPO office in Hemel Hempstead over New Years - it got there in 36 hours (on a 48 hour product). They returned it and sent the new Passport via DHL, same deal. It wasn't cheap, but it got the job done.

Thank you