I own one & have kept it completely stock. After 1911 modifications & accessories I think the 10/22 has the most listings in Brownells. The first thing I would change is the trigger. I don't compete with it, however. It remains a desert plinker.
4 each at present.
Set back the barrel, rechamber, or in one case, a new bull barrel.
Scope on 2.
Folder on one used as a survival rifle when flying. Brick of ammo stored in waterproof film canisters in my "kit."
I have had several over the years,down to 1 right now.They are a good reliable .22.I have kept all mine pretty much stock but there are a lot of after market barrels and stocks available.Back before 94 the cool set up for them was a Butler Creek folding stock,muzzle brake and 30rd mags.Now days you will pay a premium price for one of those stocks and the mags ain't cheap either.The popular mods today for them are the heavy barrels and thumb hole stocks.
I've got two of them. I have one decked out for a silhouette gun, and the other is an unmodified deluxe sporter. Both guns shoot very well and function reliably.
I agree with the comment on the 30-rnd mags. I remember buying Ramlines at gunshows at $8 each. Ahh, the good 'ole days.
For me, it is hard to beat the factory 10-round magazine. The design is simply awesome. I have a few mags that have tens of thousands of rounds through them and they still work perfectly. In my opinion, they are the best reason for buying a 10/22 over another model.
Second gun I ever owned, at age 18. Still have it, still in bone-stock configuration. Although I hardly shoot .22LR anymore, it has always been a great fun gun and a good one to start new shooters on. It's always been 100% reliable with the factory 10-rounder, but all the plastic banana clips I've tried have been junk.