A lot of people seem to think that the FORM of a URL makes more difference than the CONTENT on the server. It really doesn't.
For practical purposes, a subdomain is nearly always treated just like any other deeplink into a site, or like any other related site.
That is, "gadgets.myshop.com" is the same as "myshop.com/gadgets" is the same as "myshop-gadgets.com"
Dunno what kind of sites you're creating: if you're calling sites "completely separate" just because they don't link to each other, our response likely will be: "you don't even link to your OWN sites, why should WE link to them?" If you're calling them "completely separate" because each of them describes a separate product for sale (or service for rent), we'd call them "vanity domains/subdomains/deeplinks" (and we'd call you a spammer.)
If they're "completely separate" because you're a little web development shop selling cheap independent websites to your neighborhood businesses, or building free websites for local charities (and therefore scrimping on the cost of domain name registrations), then yes, we'd be happy to consider them all for listing -- whether deeplinks or subdomains.
BTW When you ask whether a URL gets privileged consideration simply because its on it's own subdomain or domain or server, then ... it's almost impossible to form the question in a way that isn't insulting to editors. It is logically equivalent to, and is going to sound like "Hey, I know you idiots are spotting my deeplink spam, but are you smart enough to spot it after I tweak the DNS?" And our answer has to be, "If you're calculating ANYTHING based on assumptions about how we treat URLs, then you're already a spamming weasel. And if it ever matters, we'll find out where your den is, and what kind of roadkill you had for dinner."
The basic principle is: we WILL deeplink domains that are clearly umbrellas for clearly independent sites. We'll only list ONE of a swarm of related sites, even if they're on separate domains on separate servers. And we'll even try not to be over-suspicious of subdomain names, EVEN though their most common use is as stupidly blatant spam. Beyond that, we can't go without conceding the presuppositions in your "when will you stop beating your wife?"-type question.