I think it depends on the people who are invited and what the wedding favor is. I've gone to weddings where they gave cookies with their wedding date and names on them and they all seemed to go. Everyone was eating them or giving them to someone at the wedding that wanted another one. My cousin did a little bag of m&ms and a wine glass, most of them went but some people left theirs behind. We are doing a candy buffet and giving everyone a Mason jar to fill up with the candy. I don't think I've been to one where there was no wedding favors but I have heard of people not doing them. If I was you I'd just stick with a food item like candy or cookies as a favor cause 9 times out of 10 people will definitely take the food item.
In my opinion, it depends if the favor is edible or not. When the favors are edible, guests are always eager to take these and very few get left behind. Non-edible favors are the ones that usually get left behind or thrown in the trash later.
I agree with Molly. Either do something edible, or skip them altogether. My sister had koozies as her favors, and so many of them were left behind at the end of the night (though a few people did take them!). I've seen favors that were edible, and a lot fewer of them were left behind (or if they were left behind, they were already eaten). My fiance and I are doing chocolate covered cherries as our favors, since the area we're getting married in is known for their cherries.
Favors are not cheap and so many get left behind that it makes more sense to save the money for a rainy day or put it toward food/drink/entertainment. Even edible favors get left behind. I would save your money and skip them.
Of the dozen or so weddings I've been to in the last few years, I remember two that had edible favors and one that had a non-edible favor that I actually used. I think most of the others had favors, but I couldn't tell you off the top of my head what they were. If my experience is representative, I would say it's not worth it to do something that 75% of your guests will forget about unless it's very important to you.
Personally I think they are a BIG waste of money! Between shot glasses with the couple's names on them to salt and pepper shakers, I have seen so many favours go to waste.
I agree with PP that edible favours are nice if you can be bothered. The only favour I've seen to date that I have actually used was a keyring - at one wedding I was at, they had a professional photographer going around taking photos of couples, families etc, and at the end of the night you could take home a custom keyring with the photo taken sealed in plastic. It was very sentimental.
I wouldn't waste money on it, your guests wont care! You invite them to the wedding, they thank you by giving you a gift, you thank them for coming by feeding them, you thank them for the gift with a thank you card.... how many gifts and thanks do we need to be giving? Lol. I feel like it's enough without them.
I personally think food-honey, syrup, chocolate, etc-is the only way to go. I would most likely not use a thing with the bride and grooms name, Date, etc. on it. I’m doing a frosted sugar cookie. I had a friend who made her own special cookie (her signature cookie) had it cut as a wedding bell, and froze them ahead. I guess you need to know your crowd too.
You can skip them if you want. Guests won’t miss them. If you want to do them, edible favors are your best bet. Whatever you do, don’t give inedible favors with your name and date on them (unless it’s a picture). The only inedible favor I’ve liked was a photo printed from a photo booth. There were fun props and the photo was a collage of four silly images. That was both fun and memorable!
One more thing that I forgot to add is that favors can be very simple to DIY, i.e. buy some hershey's kisses, or mints, etc. in bulk, tie them in some ribbon and tulle, and you can easily make them for under $50. If you want to have favors but budget is a concern, then I'd recommend going this route.