Good stuff Alexander, my favorite objects!
NGC 6453 is a great globular, a challenge belying its mag 9.9 brightness!
To go with the bright ones you listed, I'd like to add two globulars that are very challenging in small-medium scopes. I have seen both before in dark skies through my 4.5" reflector.
- First is NGC 6256 in Scorpius, a faint mag 11.3 globular, for me an extremely dim, smallish glow in averted vision.
- The second is NGC 6426 in Ophiuchus, a mag 11.2 globular, another extremely dim averted vision job for me.
Cheers -