One of my best soloists was a blaster, Elec/Elec/(Elec), she did 50 pretty much on her own and with relative ease. None of my scrappers did that, though a few came fairly close. My Stalkers also made it with a little help.
I have been following this Blaster/Scrapper thing on both threads, the math detail escapes me, I was never really interested in those Min/Max details, I just wanted playability.
The Arachnos/Night Widow was another one that soloed her way pretty easily to 50, as did my Arachnos Soldier/Bane Spider, she waltzed her way to 50 in record time (record for me anyway).
Tank(s) and Brute did ok, but they didn't make it to 50 without a lot of help.
Defenders, Controllers and Dominators and needed a lot of help. They absolutely sucked solo.
None of my PB or Warshades made 50, they were the worst solo for me.
I had one toon, a scrapper, who was power leveled to 50 in just a few days, I always felt guilty about it and seldom played him afterward.
But surprisingly, the toon I loved the most needed the most help to finish those last 5 levels to 50, my Ninja MM did great solo to 45, but could not go past that on her own. Folks would reject MMs for their teams seemingly automatically, and forget ITrials, no one wanted to allow Pets in ITrials.
While I understand, it made me wish longingly for a solo path to incarnate content.
That is what I would like to see the most if new content does come along, a choice of solo incarnate paths.