SK in my humble opinion is excellent. Arguably better XP content pullers than Monks, infinite aggro means you are always tanking, snare/invis/ivu/bobbing corpse are always useful, lifetaps give you something of a panic button, pet/dots are a bit of extra damage, Knight weapons/shields are generally cheap, and adding up all that gives you one of the best melee dungeon soloing classes.
Shamans are good leveling up but it's really Torpor that sends them over the top. You will be considered primarily a healer while leveling, but you will do it via slow & regen (and above all casting Cannibalize 1000s of times) more than actually healing.
Rangers are just weak. It's a DPS class that does less damage than a Warrior, let alone a Rogue or Monk. Outside the spell book is pretty good but when you move indoors and lose Harmony and Wolf Form/SoW you are down to snare and a bunch of expensive nukes that you can't cast. There are basically no worthwhile outdoor zones in Velious except PoG if you want to roleplay Chaotic Evil.
I would suggest that you keep going with the SK. A few suggestions:
- FD and splits are a huge part of the SK's toolkit. If you haven't started, start working on that. Buy stalking probes and setup your GUI so spellcasting goes to a separate window, which makes it a lot easier to time Feign Death.
- Go Sword and Board. You'll take less damage with a shield, be able to bash, and barely lose any dps as the Knight weapons are very cheap (Noctivagant Blade: 2K).
- Make the groups. If you are decent at FD splitting, you and any healer should be a group - not necessarily a great one, but most of the people that would rather sit on their butts LFG than duo suck. Log in and /w all cleric 45 55, repeat for enchanters and shaman, and gradually build up a friend list.