For those of you who don't like using commanders in lists or commander spam, I tried something over the weekend after my very lovely feel good win over BA http://www.advancedtautactica.com/viewtopic.php?f=43&t=27263&p=346430#p346430
I was going to be playing against a codex wielding opponent using Ultramarines and Papa Smurf but he's not the greatest player in the world so I tried a list with no y'varha and no commanders. It was going to be rough.
My opponent had lots of primaris in intercessors and hell blasters or whatever the plasma toting ones are and a stormraven and I had longstrike with 2 of the forgeworld HYMP hammerheads and CIB toting XV-8's. I took 3 7 man pathfinder squads with 3 ions each and darkstrider with breachers in a fish and some other stuff. Stormraven easily removed Longstrike on top of turn 1 leaving me really on the back foot as far as hammerhead synergy as well as losing a bunch of pathfinders due to bolter fire from the flying boxcar.
Long story short is I feel like we need to spend WAY too much time focusing on units for multiple turns before they are removed when you are using supbar shooting units.
This is also compounded by the fact that it is still far too easy to remove our core mechanic in markerlights when you use pathfinders. I love them but they still need something for durability before I go back to using them. Breachers definitely hurt the one squad you dump them on but they are still a one trick pony and an expensive one at that when you add in darkstrider and a fish. Ethereal still just sits around doing a whole lot of nothing even with a bunch of infantry. Papa Smurf allowing all his units to reroll everything within 6" is still soooo good that even when it was minimally used it was incredibly impactful on that portion of the board.
This thread isn't a gripe but merely insight that you are severely handicapping yourself if you don't take commanders in some form with the state our index is in. If you refuse to use them but "want to have a competitive list" you're currently out of luck. Nothing comes close to their on the board effectiveness.