For abilities that are just generally not worth having, Opening and Last Ditch are just not worth the slots, and are generally outclassed by Comeback unless you are the most amazing player in the world. Bomb Sniffer is an interesting ability, but can range from too limited to completely useless depending on the enemy loadout. I used to use Ink Saver pretty enthusiastically, but upon further inspection, its effect is too minimal, even with stacking, to be worth pursuing.
As for abilities that depend on the situation, Recon obviously requires some method of communication to be useful to your team in general, and otherwise has limited tactical use just to yourself. Quick Super Jump can be interesting on some builds, but also has to compete with quick respawn, which tends to be used under similar circumstances. Bomb Throw up has some interesting applications, but is useless on a good number of weapons for obvious reasons, and might not be worth dedicating any resources to on weapons that can use it. Tenacity is also an interesting ability, but to get the most out of it requires you to be a dominant player on your team, or at the very least a very defensive one.