... or should that be plectra I'm no good at that kind of English... to boldly go and all that.
(If you are not a guitarist here is a health warning about this post, it may lead to you attempting to chew off a limb to retain conscious or keep your sanity...)
My history of plectrum use is...
Bloody huge triangular Gibson ones, heavy, I used to wear them out so they ended up pretty much circular in a matter of days/weeks. Odd at that time I had a Strat copy and used Gibson Strings and Gibson picks - I even went for Gibson strings with a wound third at one point after reading heavier strings gave a better tone... yes but you can't play the damn thing and could never get the intonation sorted out after an older mentor showed me what that nonsense was all about.
For a long time there after I used Fender medium the hard once, often in tortoiseshell as I thought that classy for some bizarre reason. "Hello darling look at my tortoiseshell picks." I never had many girlfriends :-)
Then I had a phase of going thinner for some reason - by now I'd gone through Ernie Ball strings and then to Rotosound as my brother-in-law ran an Internet based business selling them so I got a deal. I also then went to Rotosound thins the small normal shape. I also often used Fender's of similar type, often in a blue colour. However I was breaking these left right and centre.
One day in a shop I was looking at plectrums (plectra - take your pick... geddit...) and the owner asked what I was looking for. I explained my dilemma and he suggest Jim Dunlop Tortex - as used by a lot of stars including John F of RHCP. This would have been about Californication time and I was really into his style just then. So I bought a load. By now I was back to Ernie Ball strings which I'll stick with btw - normally 10s but I do vary on the Strat and Peter Cook with 9s at times. Acoustic strings I was a Martin man for a long time but recently gone to D'Addario fairly light gauge rarely heavier than 11s.
Back to picks then and the Jim Dunlop Tortex Standard which I now use, generally the red thin ones (0.50mm) on the acoustic as I find them best for strumming and the orange ones (0.60mm) on electric. However I'm thinking of moving heavier on both, i.e. Orange for acoustic and Yellow (0.73mm) on electric, unless the electric part is very strummy (e.g. Run by Snow Patrol) or some RHCP like Californication. I tried one of my sons Yellow ones when playing Can't Stop the other day and think it help me nail the riff better.