I didn't have Qi'ra when this was first posted, but I do now and she's great. I was able to do the Smugglers Run event without her, but it wasn't a guarantee, and that I have her as the lead, I run it on auto at the highest tier.
She's also a great lead on Scoundrel teams in GA/TW, but I haven't tried her in the arena so I can't comment there. Her zeta is also one I plan to get fairly soon once I get her geared up a little more (G10 currently).
Lando was also very usefull for me earlier on in the game. He was the reason I was able to complete CH/DH at the highest tier, I used him on the Rebel team that ultimately got me Palpatine, and even had a spot on my arena squad for a while. With that said, I wouldn't use him for any of those things if I was a new player today. Building a Phoenix Squad and a BH squad will allow you do do all the things I relied on Lando to do, plus get you Thrawn, Chewbacca, and regularly finish the Rebel Roundup and Galactic Bounties events. Today's SWGOH player has little use for OG Lando, or at the very least, little reason to push him up the list of other Cantina farms that are more useful in other areas of the game or are key to their respective factions.