You're going to get difference responses from everyone, you might as well ask what oil to use in your next oil change
A quick Google search will yield a plethora of results for reviews and tests on the various EBC's on the market. Really, most work pretty well, with a few exceptions.
-I had a GReddy E-01 and loved it. Large display, easy-to-use menus, datalogging, but pricey. Also had problems with boost dropping off, but that was more turbo/wastegate actuator related than a problem with the actual solenoid.
-I've used an HKS EVC-S and I like it. Very easy to use, very slick design, works well.
-I've also used a TurboSmart EBoost2. Works incredibly well. Menu is rather difficult to navigate without getting used to it. Also looks ugly IMO and is more difficult to mount (60mm gauge form or 66mm)
-I've also used a Gizzmo EBC. Works average, menu was difficult to navigate, not really worth it IMO.