I've been using Transmit for years. I've always found it does the trick, and worked well. I recently started using Yummy FTP Pro, as one of the apps that come to me through my SetApp subscription (well worth getting, by the way; you can check it out here http://bit.ly/2ivItzh).
Yummy FTP has many great things to like about it, but I wasn't entirely keen on the multiple windows approach. Then Forklift became available through SetApp, so I gave that a go.
Forklift is an excellent FTP/SFTP client. I mostly use it for my SFTP connections, which are great when working on servers to which I have SSH access. It also supports WebDAV, Amazon S3, Google Drive, Rackspace Cloudfile, SMB, AFP, NFS, and VNC. I suspect this is really a great choice of tool when it comes to a remote file management for a developer (such as myself).
My only gripe, which is actually a big one in my books, is that it has zero ability to import Favorites / Connections from outside the app. I have close to 100 of them in Transmit. I was able to easily import them all into Yummy FTP Pro with a few clicks of the mouse. But I am left with the tedious task of manually transferring them if I want to migrate to Forklift. That's essentially why I am only using it for my few SFTP connections. I add each one in as I go along. Everything else, I continue to use Transmit or Yummy FTP with to avoid the painful migration. I consider this a major over-sight on the part of BinaryNights.
If you're just starting out with remote FTP/SFTP/Remote file management, then I'd say Forklift should be on the top of your list of apps to try for that. But if you have a large existing list of connections you need access to, I wish you luck. I'd suggest Yummy FTP Pro. It's the same price.
I've not tried Transmit 5.x (I am on 4.x), as I decided it was too expensive. But for $45 new, I don't think it has any advantages over Yummy and Forklift (both currently $30).
I am giving it 3 stars. 2 down from five, as it's not yet a viable solution for a seasoned FTP user wishing to migrate to its camp.