This question is a difficult one, and maybe the discussion even has dangers. I think the biggest danger is that someone who is in a despairing frame of mind will latch onto comments suggesting that one can go to heaven after suicide and see doing so as a way out. It's not, and no one can guarantee someone else's acceptance before God, since only He knows their heart.
I will say this. In the negative, the Lord commands us not to kill, and in the positive He commands us to love Him will all of our heart, soul, mind and strength, and to love our neighbors as ourselves. The first command is broken and the second trampled upon in the case of suicide. And it snuffs out the opportunity to repent in this life.
Plus, regardless of how many times a righteous man like Job or Jeremiah may have rued the day they were ever born, suicide was never an option for men of God. Both Moses and Elijah asked God to take their lives, but they weren't about to do so themselves. Scripture seems to accept that sometimes things get so bad that people wish they had never been born or that they would die. But the examples of those who walked most closely with God don't show suicide as an option.
Also, suicide comes from an extremely deep well of despair, and despair is a mental and emotional state in which one has lost hope. If one has lost hope, then where is faith? As David said, "I would have despaired unless I had believed that I would see the goodness of the LORD In the land of the living." Psalm 27:13 To completely give up, you have to cease believing that the Lord will answer, and that's the opposite of persevering faith. "But let him ask in faith, with no doubting, for the one who doubts is like a wave of the sea that is driven and tossed by the wind. For that person must not suppose that he will receive anything from the Lord;he is a double-minded man, unstable in all his ways." James 1:8
At the same time, not everyone who commits suicide is in a right state of mind. People can be driven to do things they might not normally do. Only the Lord will be the judge.