Having a good fireteam is almost essential for the strikes. Personally I found the Moon's Strike rather easy. Haven't really tried on a harder difficulty yet since I would be by myself and I'd have to start again the moment I die once...
One of the hardest if you ask me would be on Mars fighting the Cabal strike or Venus fighting the Vex leader. I imagine Circle of Glass (Think that is its name...) is going to be insane since I cannot even access it yet and I'm level 22 almost maxed out Bladedancer now as well.
Mars Cabal Strike was just annoying because of his minigun and missiles while having Legionaries and Phalanxes advancing on you while you're having missiles fired at you in a confined area.
Venus Vex Strike was just pretty easy looking back at it but the fireteam was pinned down in a single position but there was an impenetrable shield around the Vex boss so you had to time when to shoot.
Although I am beginning my hunt for Legendary equipment and rare or better Fusion Rifles and all the Spirit Bloom on Venus so I can upgrade my Legendary Armour. Then one day when I get everything maxed out I can be that *CENSORED* who should put the game down and fuck off but instead keep playing and fucking off the lower levels. 
I have got some more Mote of Light though only need twenty more to get a cool looking cloak...
