Rimmel Lash Accelerator £6
Bobbi Brown Waterproof and Lengthening £18
Both of these are my absolute favourite for lengthening although I do steer more towards the BB one that I've been using for the past year as the formula is longer lasting and gives a more natural feel. The Rimmel mascara can become a little bit clumpy on my eyelashes but only because I use a ridiculous amount of layers. They both do exactly what you want in a lengthening mascara and maximise your lashes as much as they physically can. Also they don't dry out super quick like benefit mascaras do which is great for people who are on a budget and can't afford to repurchase every month (which is super annoying).
Maybelline The Falsies Black Drama £8
Benefit Theyre Real £18
These are both also amazing at what they set out to do which is create thick long false like lashes without that super false look which isn't the most flattering on everyone. In my opinion The Falsies mascara is the best on the market no matter what category it's put in as it does everything and can transform any look from plain to fab. Also each tube lasts around 2/3 months and as it's the only mascara you'll ever need it can save you a few pennies. The benefit mascara is great for the few weeks the product lasts. It really does make eyelashes look amazing however it does dry out ridiculously fast which is pathetic considering how much they charge for it. I'd rather not spend £36 a month on mascara thanks!. But if you're only looking to use it now and again for nights out or special occasions I would recommend it as it's great for that sort of look, just not for everyday use.