Which is better for making yogurt?

The Instant Pot Duo 30. It has a dedicated yogurt program; the Proctor Silex has no yogurt mode.

Which pot lasts longer?

The stainless tri-ply pot on the Duo 30. Nonstick coatings on the Proctor Silex degrade with scratching and dishwashing over time.

Is the Proctor Silex easier to use?

Yes. You pick a mode and set the timer, with no preset menu to scroll through. The Duo 30 asks you to choose among 13 programs.

Do both brown meat before pressure cooking?

Yes. Both have a saute or brown function, though the stainless pot on the Duo 30 handles high heat and deglazing better than nonstick.

Is the Duo 30 worth stepping up to?

If you want yogurt, rice or preset programs, yes. If you only pressure cook and steam, the simpler Proctor Silex covers it.

How many people does a 3-quart cooker serve?

About three. Both are sized for small households or meal prep, not large families.

Instant Pot Duo 3-Quart vs Proctor Silex 3 Quart Pressure Cooker

The Instant Pot Duo 30 is the stronger pick for most people. It adds yogurt making, rice cooking and 13 named smart programs, and its stainless tri-ply pot sears better and resists scratches. The Proctor Silex is simpler and lighter on features, with a nonstick pot that wipes clean but wears faster. Owners of both praise the small footprint; the Duo 30 has the deeper track record and the longer feature list.

Choose the Instant Pot Duo 30 if you want yogurt, rice and preset programs, and prefer a stainless pot that can take years of metal utensils.
Choose the Proctor Silex 3QT if you want the simplest possible controls and a nonstick pot that cleans up in seconds.

Prices

Instant Pot Duo 3-Quart: $59.99 at Amazon (last seen Nov 10)
Proctor Silex 3 Quart Pressure Cooker: $59.99 at Amazon (last seen Nov 10)
Difference: both cost the same at the latest prices (Nov 10)