You need to really sift thru the GFCI, the best price I found locally is Menards for about 10 a piece in 3 pack and it seems to change weekly. Bought some a month ago 33$ and last week about 29 I think.
I know you are going to get all kinds of opinions on this but,,,,,,,,,,,,,,,,,,,, I been doing this a long time and when I started out would have had a different view which I found may not have been as accurate and had little experience,,,, have removed and remodeled already some of my first work, have replaced a lot of old work.
I found the cheap **** to be as reliable as the rest of it,,,, I know,,, you will hear ******** to the contrary but I cant even remember the last time I replaced a replacement or relatively recent install and have use them on work benches where they see multiples of use cycles any home shop ever would.
I have a pretty fair pool to sample and have installed hundreds for others as well as have several hundred of my own,,, 3 or 400 maybe.
At 4$ for box of 10 devices it makes it painless to add extra or do new instead of used etc. Its painless to keep a box of them on hand and when you want it got it without keeping lotso money parked. On occasion I use a "better" one mostly for the backwire feature where old boxes are crowded. If you are using steel boxes I use a lot of 4x4 as they have a huge variety of covers, if there is a chance of anything going in them except common outlet and switches such as gfci use deep ones. Some new gfci are deeper than old and a welder recept needs one.
15A are fine, I am not sure how many pieces of equipment I own but its substantially more than most suburb types and do not have a single piece with a 20 end.