I get through a lot of mascara - it never seems to last very long, and it tends to be pretty expensive, too. My current favourite is the Rimmel Sexy Curves mascara.
I used to use Max Factor 2000 Calorie mascara in black. It's just under £10, but it's a bit too thick and heavy for my liking, and always felt a bit sticky. Sometimes I'd have to use a second, dryer mascara brush to de-clump the mess left by this one.
I've tried loads of different brands, but never stuck with one out of anything more than habit until I ended up with the Rimmel one (pictured) by accident.
Personal Favourite: Rimmel
Surprisingly enough, my current favourite is one I first bought because I needed a new mascara for that evening and didn't have time to leave campus to buy one. There was a Rimmel make-up stand in the paper shop, so I picked up this Sexy Curves mascara in black for about £8.
It's a really light mascara, but makes your lashes look longer as it doesn't weigh them down. It looks natural, doesn't cause my lashes to stick together, and I don't find myself wanting to rub my eyes by late afternoon.
I think this mascara might actually last a little longer than other brands I've tried in the past, too! The brush isn't big, but it does a good job, and you don't even need to use that many layers to make a difference. I naturally have quite thick, dark eyelashes (I think it comes with being dark-haired!) so all I really need is one to make them seem longer and curvier.
I think, where makeup is concerned, the best thing to do is just keep trying different brands until you find one you like. Don't feel you have to use the same brand for everything, either - unless there's a 2-for-3 offer on in store, in which case it often pays to do so!
I have tried many brands but Maybelline Hypercurl Volum' Express maskara is best for me. The best thing is it is waterproof and stays for the entire day and add volume to the lashes.