I bought a pair of beginner Evolv climbing shoes and they have fared well, but I'm getting better and need something with aggressive heel and toe. What's the next step for a shoe?
I think you have the next step nailed down already: something with a more aggressive heel and toe. You don't mention which Evolv shoe you have, but my guess it's something like the Royale ($85), a climbing shoe designed for decent comfort and performance at a good price. A logical next step in that brand would be a shoe such as the K-lace ($110). It has a bit snugger fit than the Royale, and is aimed at sport or traditional climbers who need good smearing and edge control. Or the Optimus ($125), which ditches laces for hook-and-loop straps, has an aggressively cambered (down-turned) last, and a hook-friendly heel. That's going to be a very serious shoe for gym climbing.
In other brands, La Sportiva's Miura ($140), is a high-performance rock shoe with a sharply curved last, speed laces, and super-sticky Vibram XS outsoles. Or for something a little more all-around, try the Five Ten Anasazi Blanco shoes ($145). They don't have that radical curve, so they work well in all sorts of technical situations. Good comfort, but also good performance, plus low-stretch synthetic uppers.
Fit is super-important. Try on several pairs, ideally mid-day or during the afternoon when your feet have had a chance to swell a bit during the day. Try several sizes from the same maker, as well as the same size from different makers, to see what works best. A good piece of advice is to take them home and wear them while watching TV for an hour or so. If they still are snug but feel good, then they're probably right. If they don't feel right, then they aren't scuffed up so you can return them.