Well, you'll probably want more than one sequencer. I know. That's not what you want to hear.
I generally lump sequencers into two categories: simple and complex.
Think of a simple sequencer as an 8 or 16 step sequencer that can control CV and gate (perhaps just one of the two). The Pittsburgh Modular micro 8 step sequencer, Befacos Muxlicer, Noise Engineering Mimetic Digitalis fit the bill as well as the Sequins mode of Ornaments and Crime.
A complex sequencer would be like the Eloquencer, 1010 Music Toolbox, NerdSequencer, etc. Most of them you can save your patterns in and construct entire songs.
I would go with a couple of simple sequencers first. If they have the option to be reset/synced, they'll fold nicely into a more complex set-up.
The complex sequencer is more about personal preference. With the more complex sequencers you tend to trade off real time controls for depth and the ability to recall your work.
Don't be afraid to be wrong. Order from a place that has a great return/exchange policy. A 30 day period is usually good. You don't know what's going to work for you until you've had a chance to get in depth with it.
As far as the Neutron, keep it. You'll find it more useful as your system expands. Sometimes you want to just create a sound quickly without a lot of patching. Having an all-in-one synth voice lying around can help with your inspiration rather than trying to patch the equivalent together and losing inspiration.