No, why would I want sftp and ssh in a single application? If I want sftp I type sftp, if I want ssh, I type ssh, if that's too dang hard, I write a wrapper where I can select either.

Easy to manage servers - servers are (relatively) easy to manage. Key to a server? Thousands of servers, don't have that many keys - even if done in some kind of combination with keys, that's way too many to bother to remember anyway. I type the name of a server (or some alias (Host) or the like in configuration, I get that server. Deal with lots of servers, so I've also written (for and at work) programs that will give me server(s) based upon relevant selection criteria, e.g. operating system, version thereof, location, application, row or rack or other groping, etc., and then can feed that to simple CLI commands in, e.g. loop, do do the needed, on a single server, or half dozen, dozen ... hundreds or more ... whevever that need or ought be done. E.g.:

$ (for host in $(some_host_listing_command [args ...]); do ssh host ...; done)

And for longer running commands, I'll, e.g. create some (temporary) sudirectory, launch each in background, save stdout and/or stderr to file(s), wait for them to complete, and then examine the results. For even larger numbers of hosts, I also add some rate limiting, e.g. so it won't attempt to do too many at once and, e.g. run into resource limit issues on the client side.

Don't need no drag 'n drop, can do however many screens or terminal sessions desired, can copy/paste or otherwise get data between servers, etc. In fact, don't even need any GUI at all - sometimes that's highly advantageous for some connections or operating circumstances.