A lot depends on how you want to use it. Some folks want a very small MIDI keyboard (just an octave or two) with a USB interface for convenience and portability. Others may want a full 88-key keyboard to (try to) use Hyperscribe. Some may want to feed their keyboard through a MIDI interface rather than playing it directly into the computer via USB (even though the MIDI interface may use USB or a dedicated computer card to interface with the CPU).

I have an old Yamaha DX7 that I purchased before notation programs were even common, certainly before Finale began. It has 61 keys and can produce its own sounds. I enjoy that, since I have plugged the DX7 into an old set of external computer speakers that let me try stuff out on the MIDI kbd without using MIDI Thru in Finale; I find that convenient. I sometimes wish I had 88 keys to enter low bass notes rather than entering them an octave high and later transposing them. I do not use the MIDI Kbd for all note entry, but I would not want to be without it.

That's my experience. I hope others will chime in (& I'm sure they will) with their experience. I guess part of the question is how serious you are about your music (and therefore how much convenience you want/need and how much you want to spend on it).

If you can visit a local music store to try them out, do that. If you're going to purchase online like I did, then start googling and reading reviews. Are you primarily a keyboardist? If so, you might be drawn to a controller that mimics the weighted keys of a piano. If you're like me, I'm not proficient on piano, then a basic controller without a lot of bells and whistles works fine.

I have a 49 key controller. I preferred my previous unit which had 61 keys, but I moved to a smaller house with a smaller office and a smaller desk. I started using Finale years ago with no midi keyboard. I became very fluent and comfortable using the computer keyboard and Speedy to enter notes. In many ways I still prefer that entry method to a midi keyboard.

I ended up purchasing a Nektar controller. It works fine with Finale but I actually decided on this unit because it interfaced with Logic very nicely.

I have a midiplus musical keyboard that initially worked fine with finale but now is not.  Well if that is not compatible, what is?

I'm afraid you are going to have to tell us a lot more for us to help with your problem. What version of Finale? What computer operating system and version?

https://makemusic.zendesk.com/hc/en-us/community/posts/215729367-General-Discussion-House-Rules

What kind of MIDI interface between keyboard and computer (MIDI cable, full MIDI interface, USB cable at both ends)?

Your first option would be to restart the computer. I'm guessing you have tried that. Turning on the keyboard before starting Finale, just in case that would help. Making sure your MIDI sampling rate in Finale agrees with that on your machine.

What have you tried already to get the pair working together?