Depends on what you want from the controller.

Three questions you should ask yourself:

1. Do you want to just enter MIDI notes or do you want to play entire compositions? In other words, do you want to be EDM-artist-flavor-of-the-month, or play Chopin?

2. Do you care about a lot of controls, i.e. buttons, pads, faders? Most traditional musicians don't need them too much, but if you're creating EDM, hip-hop, etc. you kinda need them

3. What size are you comfortable with? Portable controllers are great but have tiny keys which can make playing complex melodies difficult. Full-size keyboards (49 keys and above) on the other hand take up a lot of desk space

If you want playability and have a budget, you'll do better with a digital piano instead of a plain MIDI controller. The piano will have far better keys. If you'd still go for a MIDI controller, I suggest something with semi-weighted keys. These do a better approximation of acoustic piano keys and don't always cost a bomb.

As for brands, I've never seen anyone regret buying an Akai. Their keys aren't the best but their pad quality is top notch. For keys, I suggest going for a Roland. Their A-500 Pro is a fantastic keyboard. Stay away from M-Audio; their keys have a habit of falling apart after a few heavy jam sessions. Another great but slightly expensive brand is Nektar. Their Panorama P4 is great.

If cheap is your thing and you need something small, go for an Akai MPK Mini. If you'd rather have a full set of keys, pick something from midiPlus or Nektar's GX61

This is a good overview of MIDI keyboards

Also check out this list if you're using a Mac (I know lots of musicians do)