"Which 22LR semi-auto pistol is most forgiving in terms of using the different kinds of 22LR ammo in the market?"

It is usually the variation in ammo, not the guns themselves, that cause the problems. I have been very pleased with the nine 422/622/2206/2213/2214 pistols I have owned as only the 2213 is particular about it's diet. The various Ruger, Beretta, Browning, Colt,High Standard, Walther, and Astra pistols generally all shot and functioned well with high speed ammo, but were persnickety with standard velocity stuff.

Of all the above guns, my Walther TPH was the pickiest and the Astra Constable the best (in function, accuracy, portability).