I use a Fishman Platinum Pro. My main sales pitch is that this the third one I've owned. I bought one when they first came out, and then at some point sold it to try something else out, and then went and bought another. Later, Fishman releases an updated version and I went and bought one of those. I've had multiple turns of trying to find something I like better, but always end up back with the Fishman. A huge part of that is the built in compressor, which is pure magic on an acoustic guitar. But also, low-noise, an easy to use EQ, an effects loop, a built in tuner, and a boost. The Baggs Venue is similarly great.
On the cheap though, the Behringer ADI 21, which is a flat-out rip-off of the Tech 21 acoustic DI, is one of the better $35 values you'll find. I regularly use mine at gigs where I bring along my mandolin, dulcimer and 12 string. Or if I'm running off to an open mic type thing, where I want to just plug and play (as the Fishman is part of my regular pedal board).