Quote:
It's a hard question and possibly unpopular one if you have so many coins that could be considered favourites. Of course its easy if you have a sentimental coin you love or one you had since you were 3 - but for people like me who only got serious 3 years ago and spent that time accumulating what I consider a nice collection, its hard.
Again the criteria - is it value, condition, popularity, sheer aesethics or what?

I do actually have a coin that I had since I was... well not 3 but maybe 7 or 8; possibly the first coin I consciously collected that wasn't just current circulating coinage. I'm not willing to say it could be my favorite because it's just that bad. (I should probably make a pic of it anyway.)
I guess for now I should just look through my uploaded pictures and choose a few I consider my favorites... I want to say in no particular order but they're in uploading order.
(I actually have a special padded container for coins I want to protect, and many of the coins below are stored in there. There are many coins that are in there for other reasons, though.)

Bohemia, Ferdinand II, 1/4 (kipper) kreuzer, 1622.
Numista 104706, one of very few types I added to Numista.
This was my first introduction to being able to find rare coins in low-end bargain bins; I had no idea what this was when I bought it but it looked nice.

Saint Pierre and Miquelon, 1 franc 1948, KM#1.
One of only two non-pattern coinage types from this tiny archipelago (there's also a 2 franc).
High grade, low mintage, medium-low price (I paid $3), extremely beautiful, what's not to like?
Well, the photos suck (and are the wrong way up for some reason I still don't know). But I'm not sure if it's even
possible for mere photos to transmit this coin's sheer beauty.

Elbing, Swedish occupation, Charles X Gustav, solidus, 1657
Numista 96629, Kopicki 9655 (PRVSSIAE), KM#65
Photos suck, I know. I tried a few more times but either the coin had seriously darkened since 2017 or I got lucky.
This is probably my rarest coin - it's so rare that Krause doesn't even give it a price!
(...I have another type that's not in Krause
at all, which might be slightly rarer at least for that particular date. And of course for ancients rarity is tricky.)
...I also really want to choose an ancient coin as well, but can't think of any specific one offhand, so for now I'll just post the neatest of my recent purchases.

Roman Empire, Cappadocia, Caesarea
Severus Alexander, year 5 = 225/6 AD (off flan on this example)
AE22, uncertain denomination
RPC VI 6804