I'm not sure if I have any close(ish) ESFP friends. I have one fairly close friend who I think might well be one. I have to admit that I've been kind of prejudiced against ESFPs in the past because I think I've met lots of people in big groups who behave like the worst ESFP stereotypes. However, I'm sure quite a lot of those people were other types as well, likely including a lot of ESFJs. Any types in groups all together behaving like the stereotype of one type, not a good thing...
If this friend I'm thinking of is ESFP, she's very cool and caring, is able to attract people (of either gender, in various ways) more easily than me, etc. She tends to prattle on which can be a bit annoying, but no big deal. I'm not sure if she's ESFP though. Could also be ENFP or even ENFJ.
I have a friend who I'm pretty sure is ISFP. She's great, except for a couple of frustrations: I don't think we'll ever really go that deep, and she can be a bit flaky (doesn't answer texts, etc). However...she's really laid back, genuinely tolerant in a good way, doesn't get stressed and takes things as they come, is an introvert but does "extrovert" extremely well and has a variety of friends and a good social life (a bit like me except I think she comes across more social), etc. Also artistic (a highly talented artist) and playful. A good friend to have, though we may never be super-close in the way I think of it.
I also have a probable ISTP friend. Cool guy, laid back, weird sense of humour, likes guns and bikes, more flexible morality than mine. We've had a very pleasant casual friendship with occasional moments of closeness. He really opened up to me a few times which I was touched by as I don't think he does it much (and it wasn't one of those "BE MY THERAPIST!!!!" things that has caused me problems with guys especially.)
There was nothing between us, but I have to admit that in theory at least I'd like to try having an ISTP boyfriend.

I think my ex may have been ISFP, but his main problems were/are immaturity and selfishness, which can certainly affect any type! He might also have been INFP.