good question!!! I don't have a clear answer actually haha (i kinda do?), especially because I'm not as knowledgeable on them as I'd like to be, so I'll just ramble a bit about flowers that I do like and why if that's okay!

chrysanthemums -- I have a funny association with these because the name of this flower was on the list of a spelling bee I took part in during 5th grade (I think, or it could've been between 4th-6th)... I practiced really hard to remember how to spell it! and I did! but I got second place because I forgot how to spell independence LOL... Anyway, the point is that I knew the name of the flower since young and although I can't recall when I've seen these flowers in person (probably a few times!), I thought the spelling was so lovely that I still find myself repeating it in my head quite often... I think the flowers are quite pretty and some of the meanings behind them stand out to me a lot! specifically white chrysanthemums having completely different meanings depending on the country (some associate it with grief while others with loyalty); additionally, I appointed this flower to one of my ocs (Elaine). I think the memory I have attached to the flowers (particularly the name) is why I'm quite fond of them.

baby's breath -- This flower's more fitting to the original question haha! So you can consider this my actual answer and all others (above and below) as others I love. I'm not exactly sure what drew me to them (which is often the case...) They're what sticks out to me most when I go to the supermarket and walk by the flower section. I think they're beautiful and I like how they pair well with browns (like those brown paper bouquets!!! very gorgeous!!!) I think the size of the flower also really catches my eye... I like looking at things (just like spectating life around me I guess?) and just taking in what's around me and these flowers in particular always have me looking at each tiny petal... these flowers are so cute to me... they soothe my heart..! I'm looking up the meaning behind these flowers and they're often given at weddings/to mothers, they're a symbol of purity/innocence and other similar sentiments!

hyacinths -- another flower that I don't really recall seeing in person much if at all, but also am attached to them because they kinda influenced the development of my main oc Leila (which I think the timing of this question is kinda funny given that I was thinking back to how I came to design her recently). I appointed purple hyacinths to Leila since years back and I have a feeling that those flowers were the reason why I gave her purple hair haha, that + the fact that the meaning behind them is related to feelings like forgiveness and sorrow also stood out to me! So these flowers have some sentimental value for me due to my association of them with Leila!

I think I also seem to lean towards white flowers as favorites... I do like white lilies and lily of the valley, and a somewhat recent addition to that list would be star jasmine! I used to see them a lot around my uni town and they have a pleasant smell! I didn't know what they were called until my girlfriend told me about them while we were walking haha ^^ I think she's much better at recognizing flowers than I am LOL, but it's the memory associated with them that makes star jasmine a flower I really really like as well!

I'm also realizing that a good amount of these flowers I like either have associations with purity or death in a way haha