Block connector is a simple and effective way of connecting your panel to its wiring harness. It has the advantage of only needing simple tools to work with it. It is also great when you only want to connect or disconnect one wire at a time.
Robust and long lasting, not water proof but water gets out as easy as it gets in so great when under cover.
​Main disadvantage is it takes time to connect or disconnect the whole thing.

This is the one that I choose. Snap lock connectors give you the convenience of being able to connect up a number of wires at once and if the wiring gets wet it will dry out again once conditions allow.
The main disadvantage is that you need a special crimping tool to attach the wires correctly. Though it is possible to use small pliers to do the job. 

Superseal connectors can be the best choice for connecting up the wiring on your boat. if they are put together correctly using the correct tools they do a magnificent job. However there are a number of things to think about:

1. Water and electricity  or electrical components do not mix - ever. If your wiring is getting wet these connectors will not cure the problem in the long term.
2. They are quite complex. Getting all the parts together in the correct order and locked can be a real puzzle.
3. You do need the correct crimping tool to connect the wires correctly. You crimp the wire and the little rubber seal at the same time in one action. This seals the seal itself to the wire and puts the seal in the correct position to seal into the block.
4. You must get the connector the correct way up when you insert it into the block or it will not lock.
5. You must lock the anti-pullback devices correctly or the wires WILL - 100% WILL work their way lose over time and break the connection. But the connector will look as though it is done up.
6. The big bad lost at sea problem is - They are waterproof. If water gets in it will stay in - it can not get out. This will provide the ideal conditions for corrosion but also provide a very good conductor. So from the outside they look great and work well until you pull them apart and all the metal parts have rusted away.
   

​So superseal can be the best solution to boat wiring - but check them every now and then on dry days. Also even though its a waterproof connector try to avoid them getting wet.