This would go on a .22 semi auto pistol for speed shooting, longer range plinking, etc.

My damm arthritis kicks in while shooting my .45 and 9mm, so I need a gun just to shoot a bunch.

What red dot is best for this application. The gun will have a pic rail mounting base

Oh yea, small budget, no $700 Aimpoints, etc. I've owned a Burris fast Fire II, it was "ok"

Leupold delta point?

I like my Delta Point Pro. It sits in a ADM mount on top my scorpion perfect little reflex sight for it. Really like the wake on movement feature.

You sight it in at the top point of the triangle? Aiming point?

Yes sir, but for what I use it for anywhere on the dot will still be center mass

I like the Vortex Venom 3moa that I mounted on my Glock 40 MOS.
My Scorpion wears a Vortex Spitfire 1x prism sight so I always have a reticle even if the battery is dead. But this one is more of a home defense weapon and isn’t a pistol sight. If I trust my life to it, I don’t rely on batteries. It also has a lower 1/3 co-witness with the factory sights should I need those.

So to answer your question, on a pistol I’d go with a reflex sight of some kind. Better sight picture and smaller/lighter than most red dots.