We could turn this into a mechanical pissing contest, but that's running the thread completely off topic for the OP.
If he has it broken down to 'Cocker or old Angel, the question really becomes do you like mechanical tinkering, or love soldiering? Older Angels are actually really simple markers mechanically with some interesting choices in stock electronics and batteries. You can pick up an old LED or LCD on the cheap, toss a UTB in them (9v and multiple firing modes if that's your thing,---it will fit in the third tube in the body and battery will fit in the grip frame of an LED), solder the puppy up and you're good to go. The positives are that most parts are dirt cheap including barrels. When I rebuilt one of my old LED projects, I got a full set of matched Dye UL backs for under 60. The volumizers, frames, asa's, bolts, pull pins, and feednecks are all easy to get and cheap. The noids aren't necessarily. It's totally not related, but LEDs/LCDs also seem like they were anno'ed with a sharpie, so expect it to have some scuff marks. I never see old Angels anymore, and really, they're good shooters you can get cheaply. It also can keep up with pretty much anything on the field with the current rules too.
Autocockers are fun, to tinker with and great if you prefer wrenches to soldiering irons. The parts are cheap, all over the place, and there's a ton ways to go. They're also really easy to do pump/mech/slider/swing in terms of versatility.
Both options are fun. I'm guessing you'll be happy either way.