Tierlists can be a useful guidance tool to evaluate the general strength of Heroes, but they should never be blindly followed.
Maps, synergy and counters on enemy team can influence the strength of a pick.
I made this Solo Q HL tierlist based on: personal experience (in Master+ HL), actual current win rates, the versatility of a Hero, how easily they get countered.
Order is always: Support - Specialist - Warrior - Assassin.
The most powerful of each category starts on the left, then descending.
Top tier. Good first picks or first bans. Ask your #1 pick what he/she would like to take, and ban another one.
If you're comfortable with these, they're good early picks. Don't feel forced to take them just because they rate highly.
Comfort is more important than strength. If you're comfortable with these viable Hero picks, and they fit in your draft, they're good!
If you're kind of a master at them, they can be good, but they have hard counters and are hard to fit reliably into most drafts.